Add type-refactor label

[erlend-aasland]

Although we discourage refactoring in general, there is sometimes a valid need for refactoring. Recent examples would be Irit's refactoring of the compiler and Mark Shannon's proposal for more readable type defs. We've historically also done (and are still doing) several test refactorings:

• Move test sub-packages to Lib/test cpython#54781
• Split up _testcapimodule.c cpython#93649
• Move test files into test subdirectories cpython#108303
• Split test_dis into a directory by separating generated content cpython#123361

Currently, we use type-feature for these efforts, but it may be beneficial to be able to differentiate between (real¹) features and refactorings.

Footnotes

1. user-facing ↩

[erlend-aasland]

Another example that recently appeared:

• Refactor PyUnicodeError internal C helpers cpython#127787

[picnixz]

Some other examples:

• Refactor codecs error handlers to use _PyUnicodeError_GetParams and extract complex logic into separate functions cpython#129173
• Refactor sqlite3 error handler cpython#129928
• Reorganize the JIT optimization passes. cpython#128939
• refactor the implementation of inlined comprehensions cpython#124697

There are probably more but this would at least separate what's a real feature from what's a refactorization (sometimes internal, sometimes not).