Add language support for .clang-format file

[vinchatl]

Would it possible to implement language support for the .clang-format file ?
By this I mean tooltips on options key, code completion with possible values only when typing a specific key, etc.

The GitHub Actions extension provides something similar if you don't see what I mean.

As options can vary from one version to another, this would need to adapt to the actual version of the detected clang-format utility.

But this might be something for the upstream project and not this specific extension.