Add error for invalid `TypeGuard` function

[erictraut]

A user-defined TypeGuard function (as defined in PEP 647) is invalid if it doesn't define at least one input parameter. If the function is an instance or class method, it must provide at least one input parameter beyond self or cls. This has been a source of confusion, so an error should perhaps be emitted in this case.

See python/mypy#14425.

[erictraut]

This will be included in the next release.

[erictraut]

This is included in pyright 1.1.289, which I just published. It will also be included in a future release of pylance.