Better `__repr__`

Start by reading the __repr__ implementation for XarrayContext and the code that exposes the wrapped DataFusion session context. The example shows that from_dataset produces a representation dominated by session configuration; inspect how that representation is built and what dataset details are available. Done means the context displays a concise, useful representation instead of the full configuration dump; the issue names no test to run.

ds = xr.tutorial.open_dataset('air_temperature')
ds

Returns a readable HTML repr:

ds = xr.tutorial.open_dataset('air_temperature')
ctx = xql.XarrayContext()
ctx.from_dataset('air', ds, chunks=dict(time=10))

Returns too much unnecessary info:

SessionContext: id=e1ae5d13-ba2b-4ab3-81d0-b523b0dd93e4; configs=[
	datafusion.catalog.create_default_catalog_and_schema = true
	datafusion.catalog.default_catalog = datafusion
	datafusion.catalog.default_schema = public
	datafusion.catalog.has_header = true
	datafusion.catalog.information_schema = true
	datafusion.catalog.newlines_in_values = false
	datafusion.execution.batch_size = 8192
	datafusion.execution.coalesce_batches = true
	datafusion.execution.collect_statistics = true
	datafusion.execution.enable_ansi_mode = false
	datafusion.execution.enable_recursive_ctes = true
	datafusion.execution.enforce_batch_size_in_joins = false
	datafusion.execution.keep_partition_by_columns = false
	datafusion.execution.listing_table_factory_infer_partitions = true
	datafusion.execution.listing_table_ignore_subdirectory = true
	datafusion.execution.max_buffered_batches_per_output_file = 2
	datafusion.execution.max_spill_file_size_bytes = 134217728
	datafusion.execution.meta_fetch_concurrency = 32
	datafusion.execution.minimum_parallel_output_files = 4
	datafusion.execution.objectstore_writer_buffer_size = 10485760
	datafusion.execution.parquet.allow_single_file_parallelism = true
	datafusion.execution.parquet.binary_as_string = false
	datafusion.execution.parquet.bloom_filter_on_read = true
	datafusion.execution.parquet.bloom_filter_on_write = false
	datafusion.execution.parquet.column_index_truncate_length = 64
	datafusion.execution.parquet.compression = zstd(3)
	datafusion.execution.parquet.created_by = datafusion version 52.1.0
	datafusion.execution.parquet.data_page_row_count_limit = 20000
	datafusion.execution.parquet.data_pagesize_limit = 1048576
	datafusion.execution.parquet.dictionary_enabled = true
	datafusion.execution.parquet.dictionary_page_size_limit = 1048576
	datafusion.execution.parquet.enable_page_index = true
	datafusion.execution.parquet.force_filter_selections = false
	datafusion.execution.parquet.max_row_group_size = 1048576
	datafusion.execution.parquet.maximum_buffered_record_batches_per_stream = 2
	datafusion.execution.parquet.maximum_parallel_row_group_writers = 1
	datafusion.execution.parquet.metadata_size_hint = 524288
	datafusion.execution.parquet.pruning = true
	datafusion.execution.parquet.pushdown_filters = false
	datafusion.execution.parquet.reorder_filters = false
	datafusion.execution.parquet.schema_force_view_types = true
	datafusion.execution.parquet.skip_arrow_metadata = false
	datafusion.execution.parquet.skip_metadata = true
	datafusion.execution.parquet.statistics_enabled = page
	datafusion.execution.parquet.statistics_truncate_length = 64
	datafusion.execution.parquet.write_batch_size = 1024
	datafusion.execution.parquet.writer_version = 1.0
	datafusion.execution.planning_concurrency = 12
	datafusion.execution.skip_partial_aggregation_probe_ratio_threshold = 0.8
	datafusion.execution.skip_partial_aggregation_probe_rows_threshold = 100000
	datafusion.execution.skip_physical_aggregate_schema_check = false
	datafusion.execution.soft_max_rows_per_output_file = 50000000
	datafusion.execution.sort_in_place_threshold_bytes = 1048576
	datafusion.execution.sort_spill_reservation_bytes = 10485760
	datafusion.execution.spill_compression = uncompressed
	datafusion.execution.split_file_groups_by_statistics = false
	datafusion.execution.target_partitions = 12
	datafusion.execution.use_row_number_estimates_to_optimize_partitioning = false
	datafusion.explain.analyze_level = dev
	datafusion.explain.format = indent
	datafusion.explain.logical_plan_only = false
	datafusion.explain.physical_plan_only = false
	datafusion.explain.show_schema = false
	datafusion.explain.show_sizes = true
	datafusion.explain.show_statistics = false
	datafusion.explain.tree_maximum_render_width = 240
	datafusion.format.date_format = %Y-%m-%d
	datafusion.format.datetime_format = %Y-%m-%dT%H:%M:%S%.f
	datafusion.format.duration_format = pretty
	datafusion.format.null = 
	datafusion.format.safe = true
	datafusion.format.time_format = %H:%M:%S%.f
	datafusion.format.timestamp_format = %Y-%m-%dT%H:%M:%S%.f
	datafusion.format.types_info = false
	datafusion.optimizer.allow_symmetric_joins_without_pruning = true
	datafusion.optimizer.default_filter_selectivity = 20
	datafusion.optimizer.enable_aggregate_dynamic_filter_pushdown = true
	datafusion.optimizer.enable_distinct_aggregation_soft_limit = true
	datafusion.optimizer.enable_dynamic_filter_pushdown = true
	datafusion.optimizer.enable_join_dynamic_filter_pushdown = true
	datafusion.optimizer.enable_piecewise_merge_join = false
	datafusion.optimizer.enable_round_robin_repartition = true
	datafusion.optimizer.enable_sort_pushdown = true
	datafusion.optimizer.enable_topk_aggregation = true
	datafusion.optimizer.enable_topk_dynamic_filter_pushdown = true
	datafusion.optimizer.enable_window_limits = true
	datafusion.optimizer.expand_views_at_output = false
	datafusion.optimizer.filter_null_join_keys = false
	datafusion.optimizer.hash_join_inlist_pushdown_max_distinct_values = 150
	datafusion.optimizer.hash_join_inlist_pushdown_max_size = 131072
	datafusion.optimizer.hash_join_single_partition_threshold = 1048576
	datafusion.optimizer.hash_join_single_partition_threshold_rows = 131072
	datafusion.optimizer.max_passes = 3
	datafusion.optimizer.prefer_existing_sort = false
	datafusion.optimizer.prefer_existing_union = false
	datafusion.optimizer.prefer_hash_join = true
	datafusion.optimizer.preserve_file_partitions = 0
	datafusion.optimizer.repartition_aggregations = true
	datafusion.optimizer.repartition_file_min_size = 10485760
	datafusion.optimizer.repartition_file_scans = true
	datafusion.optimizer.repartition_joins = true
	datafusion.optimizer.repartition_sorts = true
	datafusion.optimizer.repartition_windows = true
	datafusion.optimizer.skip_failed_rules = false
	datafusion.optimizer.subset_repartition_threshold = 4
	datafusion.optimizer.top_down_join_key_reordering = true
	datafusion.sql_parser.collect_spans = false
	datafusion.sql_parser.default_null_ordering = nulls_max
	datafusion.sql_parser.dialect = generic
	datafusion.sql_parser.enable_ident_normalization = true
	datafusion.sql_parser.enable_options_value_normalization = false
	datafusion.sql_parser.map_string_types_to_utf8view = true
	datafusion.sql_parser.parse_float_as_decimal = false
	datafusion.sql_parser.recursion_limit = 50
	datafusion.sql_parser.support_varchar_with_length = true]