More Transform/Compression Examples

We need a bit more transform/compression examples in both the manual and example codes.

I also realized that we can set Dataset::setCustomTransform which is only handled in ADIOS1 right now. And the Dataset::setCompression options handled in ADIOS2 are a bit too simple (name + level) for the complex blosc and zfp parameters.

For defaults, the ADIOS2 implementation for compression/operators is still incomplete: https://openpmd-api.readthedocs.io/en/0.12.0-alpha/details/backendconfig.html#configuration-structure-per-backend

See also open to do points in: #569