Support data sets in data provider

Even primitive detection (without pointing the method the provider belongs to) of yielded keys as named dataset

    (yield_expression
      (array_element_initializer
        (string
          (string_value) @dataset )))

could prove helpful in tests where yield is used in data provider.

At the moment I need some free time to answer myself how to pass the data set here https://github.com/olimorris/neotest-phpunit/blob/5799a4ea84450af14461d24edbde43913f9b3008/lua/neotest-phpunit/init.lua#L137-L141 or into any better place and (optionally) how to list detected data set on the summary view. Any hints (as well as PR) can be helpful.