Fix implement-interface codefix for invalid interface types

[danyalahmed1995]

Fixes #63465

This updates the implement-interface codefix so it is not offered when the implemented interface reference or required member types are already semantically invalid.

The existing fourslash coverage already documented these cases as undesirable, but still expected the fix to be available. This PR updates those tests to assert that no codefix is offered for:

• invalid type argument instantiation
• unresolved member type symbols

Validation:

• npx.cmd hereby runtests --tests=tests/cases/fourslash/codeFixClassImplementInterfaceTypeParamInstantiateError.ts --light=false
• npx.cmd hereby runtests --tests=tests/cases/fourslash/codeFixClassImplementInterfaceUndeclaredSymbol.ts --light=false
• npx.cmd hereby runtests --tests=tests/cases/fourslash/codeFixClassImplementInterfaceTypeParamInstantiateNumber.ts --light=false
• git diff --check

[Copilot]

Pull request overview

This PR updates the “Implement interface” codefix to avoid offering or applying the fix when the implemented interface reference (e.g. invalid type arguments) or required member types are already semantically invalid (e.g. unresolved type symbols), aligning behavior with the intent documented by existing fourslash tests.

Changes:

• Add semantic-diagnostics gating in fixClassIncorrectlyImplementsInterface to suppress the fix when the implemented type or its required members have blocking semantic errors.
• Update existing fourslash tests to assert that no codefix is offered for invalid type argument instantiations and unresolved member type symbols.

Reviewed changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated 1 comment.

File	Description
src/services/codefixes/fixClassIncorrectlyImplementsInterface.ts	Adds semantic error checks to prevent offering the implement-interface fix when interface/member types are already invalid.
tests/cases/fourslash/codeFixClassImplementInterfaceUndeclaredSymbol.ts	Updates expectations to assert no codefix is offered when required member types reference an undeclared symbol.
tests/cases/fourslash/codeFixClassImplementInterfaceTypeParamInstantiateError.ts	Updates expectations to assert no codefix is offered when the implemented interface instantiation is semantically invalid.