[FR](format): Let users control the association of language to file patterns

### What is the current behavior?

Since https://github.com/aspect-build/rules_lint/pull/105 we use the exhaustive list of file patterns from GitHub-linguist

### Describe the feature

You might want to reduce it, for example if your `BUCK` file uses typed starlark syntax, it might not work with the buildifier formatter.

Start by tracing the exhaustive file-pattern list introduced by rules_lint#105 and the formatter-selection path. Identify where language-to-pattern associations are configured, then verify that users can reduce the defaults without breaking existing formatter selection, including the BUCK/Starlark case.

Written by the indexing model from the issue text.