[ty] support generic aliases in type[...], like type[C[int]] (#21552)

Closes https://github.com/astral-sh/ty/issues/1101.

crates/ty_python_semantic/resources/mdtest/diagnostics/same_names.md

@@ -171,7 +171,7 @@ class Config:
 import generic_a
 import generic_b
 
-# TODO should be error: [invalid-assignment] "Object of type `<class 'generic_b.Container[int]'>` is not assignable to `type[generic_a.Container[int]]`"
+# error: [invalid-assignment] "Object of type `<class 'generic_b.Container[int]'>` is not assignable to `type[generic_a.Container[int]]`"
 container: type[generic_a.Container[int]] = generic_b.Container[int]
 ```
 

crates/ty_python_semantic/resources/mdtest/type_of/basic.md

@@ -174,6 +174,39 @@ def _(x: Foo[int], y: Bar[str], z: list[bytes]):
     reveal_type(type(z))  # revealed: type[list[bytes]]
 ```
 
+## Checking generic `type[]` types
+
+```toml
+[environment]
+python-version = "3.12"
+```
+
+```py
+class C[T]:
+    pass
+
+class D[T]:
+    pass
+
+var: type[C[int]] = C[int]
+var: type[C[int]] = D[int]  # error: [invalid-assignment] "Object of type `<class 'D[int]'>` is not assignable to `type[C[int]]`"
+```
+
+However, generic `Protocol` classes are still TODO:
+
+```py
+from typing import Protocol
+
+class Proto[U](Protocol):
+    def some_method(self): ...
+
+# TODO: should be error: [invalid-assignment]
+var: type[Proto[int]] = C[int]
+
+def _(p: type[Proto[int]]):
+    reveal_type(p)  # revealed: type[@Todo(type[T] for protocols)]
+```
+
 ## `@final` classes
 
 `type[]` types are eagerly converted to class-literal types if a class decorated with `@final` is

crates/ty_python_semantic/resources/mdtest/type_properties/is_assignable_to.md

@@ -243,13 +243,13 @@ static_assert(is_assignable_to(TypeOf[Bar[int]], type[Foo[int]]))
 static_assert(is_assignable_to(TypeOf[Bar[bool]], type[Foo[int]]))
 static_assert(is_assignable_to(TypeOf[Bar], type[Foo[int]]))
 static_assert(is_assignable_to(TypeOf[Bar[Any]], type[Foo[int]]))
+static_assert(is_assignable_to(TypeOf[Bar[Unknown]], type[Foo[int]]))
 static_assert(is_assignable_to(TypeOf[Bar], type[Foo]))
 static_assert(is_assignable_to(TypeOf[Bar[Any]], type[Foo[Any]]))
 static_assert(is_assignable_to(TypeOf[Bar[Any]], type[Foo[int]]))
 
-# TODO: these should pass (all subscripts inside `type[]` type expressions are currently TODO types)
-static_assert(not is_assignable_to(TypeOf[Bar[int]], type[Foo[bool]]))  # error: [static-assert-error]
-static_assert(not is_assignable_to(TypeOf[Foo[bool]], type[Bar[int]]))  # error: [static-assert-error]
+static_assert(not is_assignable_to(TypeOf[Bar[int]], type[Foo[bool]]))
+static_assert(not is_assignable_to(TypeOf[Foo[bool]], type[Bar[int]]))
 ```
 
 ## `type[]` is not assignable to types disjoint from `builtins.type`