[red-knot] No errors for definitions of `TypedDict`s (#17674)
## Summary
Do not emit errors when defining `TypedDict`s:
```py
from typing_extensions import TypedDict
# No error here
class Person(TypedDict):
name: str
age: int | None
# No error for this alternative syntax
Message = TypedDict("Message", {"id": int, "content": str})
```
## Ecosystem analysis
* Removes ~ 450 false positives for `TypedDict` definitions.
* Changes a few diagnostic messages.
* Adds a few (< 10) false positives, for example:
```diff
+ error[lint:unresolved-attribute]
/tmp/mypy_primer/projects/hydra-zen/src/hydra_zen/structured_configs/_utils.py:262:5:
Type `Literal[DataclassOptions]` has no attribute `__required_keys__`
+ error[lint:unresolved-attribute]
/tmp/mypy_primer/projects/hydra-zen/src/hydra_zen/structured_configs/_utils.py:262:42:
Type `Literal[DataclassOptions]` has no attribute `__optional_keys__`
```
* New true positive
https://github.com/zulip/zulip/blob/4f8263cd7f4d00fc9b9e7d687ab98b0cc8737308/corporate/lib/remote_billing_util.py#L155-L157
```diff
+ error[lint:invalid-assignment]
/tmp/mypy_primer/projects/zulip/corporate/lib/remote_billing_util.py:155:5:
Object of type `RemoteBillingIdentityDict | LegacyServerIdentityDict |
None` is not assignable to `LegacyServerIdentityDict | None`
```
## Test Plan
New Markdown tests
