Fix min_ident_chars: ignore on trait impl.

[t-webber]

fixes #13396

changelog: [min_ident_chars]: ignore lint when implementing a trait, to respect [renamed_function_params]

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[github-actions]

Lintcheck changes for baded8c

Lint	Added	Removed	Changed
clippy::min_ident_chars	0	2453	39

This comment will be updated if you push new changes

[samueltardieu]

For a local trait, it should warn about the short parameter name in the trait method definition. I don't see a test for this, and I suspect it won't warn. To suppress warnings about trait implementations, we should ensure it warns at the trait definition so that users are warned at least once about the usage of short identifiers.