Refactor: merge duplicate HasTypeVars query visitors

[brianschubert]

mypy.checkexpr.HasTypeVarQuery has only one usage and is virtually¹ identical to mypy.types.HasTypeVars. Merging them seems sensible. The latter has wider usage via has_type_vars, so it seems like the better one to keep.

Some history for the record:

• mypy.checkexpr.HasTypeVarQuery was added in 12 years ago a40efb4
• mypy.types.HasTypeVars was added 5 years ago in 59617e8

Footnotes

1. the only difference is that HasTypeVars sets self.skip_alias_target = True, but this seem to fit the usage of HasTypeVarQuery just as well. ↩

[github-actions]

According to mypy_primer, this change doesn't affect type check results on a corpus of open source code. ✅

[hauntsaninja]

🧹