PY-48009 Control spaces around "=" in keyword patterns with an existing setting

Namely, they are formatted in the same way as keyword arguments. The name of
the option doesn't reflect so far, though, because it requires UI changes after
the freeze.

GitOrigin-RevId: 8fa079ebb1b919b8f0fe7bee670a643a0b20f888

python/testData/formatter/spacesAroundEqualSignsInKeywordPatterns_after.py

@@ -1,3 +1,3 @@
 match x:
-    case Class(foo=1, bar=2):
+    case Class(foo = 1, bar = 2):
         pass