[ty] Support async/await, async with and yield from (#19595)

## Summary

- Add support for the return types of `async` functions
- Add type inference for `await` expressions
- Add support for `async with` / async context managers
- Add support for `yield from` expressions

This PR is generally lacking proper error handling in some cases (e.g.
illegal `__await__` attributes). I'm planning to work on this in a
follow-up.

part of https://github.com/astral-sh/ty/issues/151

closes https://github.com/astral-sh/ty/issues/736

## Ecosystem

There are a lot of true positives on `prefect` which look similar to:
```diff
prefect (https://github.com/PrefectHQ/prefect)
+ src/integrations/prefect-aws/tests/workers/test_ecs_worker.py:406:12: error[unresolved-attribute] Type `str` has no attribute `status_code`
```

This is due to a wrong return type annotation
[here](e926b8c4c1/src/integrations/prefect-aws/tests/workers/test_ecs_worker.py (L355-L391)).

```diff
mitmproxy (https://github.com/mitmproxy/mitmproxy)
+ test/mitmproxy/addons/test_clientplayback.py:18:1: error[invalid-argument-type] Argument to function `asynccontextmanager` is incorrect: Expected `(...) -> AsyncIterator[Unknown]`, found `def tcp_server(handle_conn, **server_args) -> Unknown | tuple[str, int]`
```


[This](a4d794c59a/test/mitmproxy/addons/test_clientplayback.py (L18-L19))
is a true positive. That function should return
`AsyncIterator[Address]`, not `Address`.

I looked through almost all of the other new diagnostics and they all
look like known problems or true positives.

## Typing conformance

The typing conformance diff looks good.

## Test Plan

New Markdown tests

crates/ty_python_semantic/resources/mdtest/expression/yield_and_yield_from.md

@@ -0,0 +1,130 @@
+# `yield` and `yield from`
+
+## Basic `yield` and `yield from`
+
+The type of a `yield` expression is the "send" type of the generator function. The type of a
+`yield from` expression is the return type of the inner generator:
+
+```py
+from typing import Generator
+
+def inner_generator() -> Generator[int, bytes, str]:
+    yield 1
+    yield 2
+    x = yield 3
+
+    # TODO: this should be `bytes`
+    reveal_type(x)  # revealed: @Todo(yield expressions)
+
+    return "done"
+
+def outer_generator():
+    result = yield from inner_generator()
+    reveal_type(result)  # revealed: str
+```
+
+## `yield from` with a custom iterable
+
+`yield from` can also be used with custom iterable types. In that case, the type of the `yield from`
+expression can not be determined
+
+```py
+from typing import Generator, TypeVar, Generic
+
+T = TypeVar("T")
+
+class OnceIterator(Generic[T]):
+    def __init__(self, value: T):
+        self.value = value
+        self.returned = False
+
+    def __next__(self) -> T:
+        if self.returned:
+            raise StopIteration(42)
+
+        self.returned = True
+        return self.value
+
+class Once(Generic[T]):
+    def __init__(self, value: T):
+        self.value = value
+
+    def __iter__(self) -> OnceIterator[T]:
+        return OnceIterator(self.value)
+
+for x in Once("a"):
+    reveal_type(x)  # revealed: str
+
+def generator() -> Generator:
+    result = yield from Once("a")
+
+    # At runtime, the value of `result` will be the `.value` attribute of the `StopIteration`
+    # error raised by `OnceIterator` to signal to the interpreter that the iterator has been
+    # exhausted. Here that will always be 42, but this information cannot be captured in the
+    # signature of `OnceIterator.__next__`, since exceptions lie outside the type signature.
+    # We therefore just infer `Unknown` here.
+    #
+    # If the `StopIteration` error in `OnceIterator.__next__` had been simply `raise StopIteration`
+    # (the more common case), then the `.value` attribute of the `StopIteration` instance
+    # would default to `None`.
+    reveal_type(result)  # revealed: Unknown
+```
+
+## `yield from` with a generator that return `types.GeneratorType`
+
+`types.GeneratorType` is a nominal type that implements the `typing.Generator` protocol:
+
+```py
+from types import GeneratorType
+
+def inner_generator() -> GeneratorType[int, bytes, str]:
+    yield 1
+    yield 2
+    x = yield 3
+
+    # TODO: this should be `bytes`
+    reveal_type(x)  # revealed: @Todo(yield expressions)
+
+    return "done"
+
+def outer_generator():
+    result = yield from inner_generator()
+    reveal_type(result)  # revealed: str
+```
+
+## Error cases
+
+### Non-iterable type
+
+```py
+from typing import Generator
+
+def generator() -> Generator:
+    yield from 42  # error: [not-iterable] "Object of type `Literal[42]` is not iterable"
+```
+
+### Invalid `yield` type
+
+```py
+from typing import Generator
+
+# TODO: This should be an error. Claims to yield `int`, but yields `str`.
+def invalid_generator() -> Generator[int, None, None]:
+    yield "not an int"  # This should be an `int`
+```
+
+### Invalid return type
+
+```py
+from typing import Generator
+
+# TODO: should emit an error (does not return `str`)
+def invalid_generator1() -> Generator[int, None, str]:
+    yield 1
+
+# TODO: should emit an error (does not return `int`)
+def invalid_generator2() -> Generator[int, None, None]:
+    yield 1
+
+    return "done"
+```