Make more type expressions valid in PEP 695 aliases and runtime contexts

[JukkaL]

Previously some type expressions, when used as the value of a PEP 695 type alias or in an expression context, generated errors, even if the code would work at runtime. Improve type inference of types in expression contexts (this includes PEP 695 type aliases) to better reflect runtime behavior.

This is still not perfect, since we don't have precise types for everything in stubs. Use typing._SpecialForm as a fallback, as it supports indexing and | operations, which are supported for types.

Also update stubs used in tests to better match typeshed stubs. In particular, provide _SpecialForm and define Any = object(), similar to typeshed.

[github-actions]

Diff from mypy_primer, showing the effect of this PR on open source code:

steam.py (https://github.com/Gobot1234/steam.py)
- steam/ext/commands/converters.py:510: error: Incompatible types in assignment (expression has type "object", variable has type "type[T]")  [assignment]
+ steam/ext/commands/converters.py:510: error: Incompatible types in assignment (expression has type "<typing special form>", variable has type "type[T]")  [assignment]

mypy (https://github.com/python/mypy)
+ mypy/stubgenc.py:736: error: Non-overlapping identity check (left operand type: "type", right operand type: "<typing special form>")  [comparison-overlap]
+ mypy/stubgenc.py:736: note: See https://mypy.rtfd.io/en/stable/_refs.html#code-comparison-overlap for more info

Tanjun (https://github.com/FasterSpeeding/Tanjun)
- tanjun/annotations.py:1601: error: Incompatible return value type (got "object", expected "type[_T]")  [return-value]
+ tanjun/annotations.py:1601: error: Incompatible return value type (got "<typing special form>", expected "type[_T]")  [return-value]
- tanjun/annotations.py:1853: error: Incompatible return value type (got "object", expected "type[str]")  [return-value]
+ tanjun/annotations.py:1853: error: Incompatible return value type (got "<typing special form>", expected "type[str]")  [return-value]
- tanjun/annotations.py:2211: error: Argument 1 to "_annotated" has incompatible type "object"; expected "type[Never]"  [arg-type]
+ tanjun/annotations.py:2211: error: Argument 1 to "_annotated" has incompatible type "<typing special form>"; expected "type[Never]"  [arg-type]
- tanjun/annotations.py:2273: error: Incompatible return value type (got "object", expected "type[PartialChannel]")  [return-value]
+ tanjun/annotations.py:2273: error: Incompatible return value type (got "<typing special form>", expected "type[PartialChannel]")  [return-value]

pydantic (https://github.com/samuelcolvin/pydantic)
- pydantic/dataclasses.py:228: error: Incompatible types in assignment (expression has type "tuple[type[StandardDataclass], object]", variable has type "tuple[type[StandardDataclass]]")  [assignment]
+ pydantic/dataclasses.py:228: error: Incompatible types in assignment (expression has type "tuple[type[StandardDataclass], <typing special form>]", variable has type "tuple[type[StandardDataclass]]")  [assignment]

discord.py (https://github.com/Rapptz/discord.py)
- discord/utils.py:1092: error: "object" has no attribute "__args__"  [attr-defined]
+ discord/utils.py:1092: error: "<typing special form>" has no attribute "__args__"  [attr-defined]

ibis (https://github.com/ibis-project/ibis)
+ ibis/expr/operations/__init__.py:13: error: Incompatible import of "Any" (imported name has type "type[ibis.expr.operations.reductions.Any]", local name has type "<typing special form>")  [assignment]
- ibis/expr/types/logical.py:351: error: "object" not callable  [operator]
+ ibis/expr/types/logical.py:351: error: "<typing special form>" not callable  [operator]

hydra-zen (https://github.com/mit-ll-responsible-ai/hydra-zen)
- src/hydra_zen/structured_configs/_implementations.py:861: error: The type "type[list[Any]]" is not generic and not indexable  [misc]

[JukkaL]

All the mypy_primer changes seem fine. Summary of what's changed:

• The object typing.Any is no longer considered a type. Since Any doesn't support isinstance checks, unlike regular type objects, this seems reasonable.
• Various messages have <typing special form> instead of object, which is more informative.
• One false positive is fixed in hydra-zen.

[JukkaL]

I'm waiting for a review until tomorrow.