[Compatibility] Add Refinement#refined_class

[itarato]

Note: Depends on #3093 (this PR requires the Module#refinements method to exist from that PR).

Source: #3039

Refinement#refined_class has been added. [Feature #12737]

[eregon]

The Primitive name should reflect in which module/class it's defined, so it should be refinement_refined_class.
Ideally it'd be a CoreMethod though, for that we need to add RefinementNodes, which I think makes sense.
We should then move the refinement_import_methods Primitive there.

[andrykonchin]

suggestion: it makes sense to have moving the class into a separate file committed separately.

[eregon]

MRI tests fail with:

  1) Error:
TestRefinement#test_refined_class:
NoMethodError: undefined method `refinements' for #<Module:0x16da3f8>
    /b/b/e/main/test/mri/tests/ruby/test_refinement.rb:1839:in `test_refined_class'

[itarato]

MRI tests fail with:

  1) Error:
TestRefinement#test_refined_class:
NoMethodError: undefined method `refinements' for #<Module:0x16da3f8>
    /b/b/e/main/test/mri/tests/ruby/test_refinement.rb:1839:in `test_refined_class'

@eregon Added a note to the description - this PR depends on #3093

[eregon]

I have rebased and pushed that to https://github.com/oracle/truffleruby/tree/feature/PA-3039-Refinement-refined_class
You can update this PR to that commit, so then when it merges it's marked as Merged and not Closed (I cannot push to Shopify/truffleruby).

[eregon]

The MRI test fails transiently:

  1) Failure:
TestRefinement#test_refined_class [/Users/graal/slave/e/main/test/mri/tests/ruby/test_refinement.rb:1863]:
<Integer> expected but was
<String>.

Because the order is unspecified.
TBH MRI tests are such a pain to deal with, let's focus on specs. I'll just tag this test.

[eregon]

Merged in ec4bbc5