Duplicated `TypedDict` assignability diagnostics

[ibraheemdev]

See astral-sh/ruff#21238 (comment). In cases where we may perform multi-inference, or don't have access to the RHS expression, we emit a diagnostic for TypedDict assignability as well as the existing invalid-key diagnostic.

class Person(TypedDict):
    name: str

# error: [invalid-argument-type]
# error: [invalid-argument-type] "Invalid argument to key "name" with declared type `str` on TypedDict `Person`: value of type `None`"
accepts_person({"name": None})

Ideally we could avoid the former.