[red-knot] Add initial support for * imports (#16923)

## Summary

This PR adds initial support for `*` imports to red-knot. The approach
is to implement a standalone query, called from semantic indexing, that
visits the module referenced by the `*` import and collects all
global-scope public names that will be imported by the `*` import. The
`SemanticIndexBuilder` then adds separate definitions for each of these
names, all keyed to the same `ast::Alias` node that represents the `*`
import.

There are many pieces of `*`-import semantics that are still yet to be
done, even with this PR:
- This PR does not attempt to implement any of the semantics to do with
`__all__`. (If a module defines `__all__`, then only the symbols
included in `__all__` are imported, _not_ all public global-scope
symbols.
- With the logic implemented in this PR as it currently stands, we
sometimes incorrectly consider a symbol bound even though it is defined
in a branch that is statically known to be dead code, e.g. (assuming the
target Python version is set to 3.11):

  ```py
  # a.py

  import sys

  if sys.version_info < (3, 10):
      class Foo: ...

  ```

  ```py
  # b.py

  from a import *

  print(Foo)  # this is unbound at runtime on 3.11,
# but we currently consider it bound with the logic in this PR
  ```

Implementing these features is important, but is for now deferred to
followup PRs.

Many thanks to @ntBre, who contributed to this PR in a pairing session
on Friday!

## Test Plan

Assertions in existing mdtests are adjusted, and several new ones are
added.

Author: AlexWaygood

crates/red_knot_python_semantic/resources/mdtest/annotations/callable.md

@@ -4,8 +4,10 @@ References:
 
 - <https://typing.readthedocs.io/en/latest/spec/callables.html#callable>
 
-TODO: Use `collections.abc` as importing from `typing` is deprecated but this requires support for
-`*` imports. See: <https://docs.python.org/3/library/typing.html#deprecated-aliases>.
+Note that `typing.Callable` is deprecated at runtime, in favour of `collections.abc.Callable` (see:
+<https://docs.python.org/3/library/typing.html#deprecated-aliases>). However, removal of
+`typing.Callable` is not currently planned, and the canonical location of the stub for the symbol in
+typeshed is still `typing.pyi`.
 
 ## Invalid forms
 

crates/red_knot_python_semantic/resources/mdtest/annotations/stdlib_typing_aliases.md

@@ -81,8 +81,7 @@ reveal_type(DictSubclass.__mro__)
 
 class SetSubclass(typing.Set): ...
 
-# TODO: should have `Generic`, should not have `Unknown`
-# revealed: tuple[Literal[SetSubclass], Literal[set], Unknown, Literal[object]]
+# revealed: tuple[Literal[SetSubclass], Literal[set], Literal[MutableSet], Literal[AbstractSet], Literal[Collection], Literal[Iterable], Literal[Container], @Todo(protocol), Literal[object]]
 reveal_type(SetSubclass.__mro__)
 
 class FrozenSetSubclass(typing.FrozenSet): ...
@@ -114,8 +113,7 @@ reveal_type(DefaultDictSubclass.__mro__)
 
 class DequeSubclass(typing.Deque): ...
 
-# TODO: Should be (DequeSubclass, deque, MutableSequence, Sequence, Reversible, Collection, Sized, Iterable, Container, Generic, object)
-# revealed: tuple[Literal[DequeSubclass], Literal[deque], Unknown, Literal[object]]
+# revealed: tuple[Literal[DequeSubclass], Literal[deque], Literal[MutableSequence], Literal[Sequence], Literal[Reversible], Literal[Collection], Literal[Iterable], Literal[Container], @Todo(protocol), Literal[object]]
 reveal_type(DequeSubclass.__mro__)
 
 class OrderedDictSubclass(typing.OrderedDict): ...

crates/red_knot_python_semantic/resources/mdtest/attributes.md

@@ -551,6 +551,7 @@ reveal_type(C().x)  # revealed: str
 class C:
     def __init__(self) -> None:
         # error: [too-many-positional-arguments]
+        # error: [invalid-argument-type]
         self.x: int = len(1, 2, 3)
 ```
 

crates/red_knot_python_semantic/resources/mdtest/expression/len.md

@@ -229,6 +229,6 @@ reveal_type(len(SecondRequiredArgument()))  # revealed: Literal[1]
 ```py
 class NoDunderLen: ...
 
-# TODO: Emit a diagnostic
+# error: [invalid-argument-type]
 reveal_type(len(NoDunderLen()))  # revealed: int
 ```