Add clang-format to CI

[unterumarmung]

Example: https://github.com/YACLib/YACLib/blob/main/.github/workflows/clang-format.yml

[b1ackviking]

One way to add a clang-format and a bunch of other checks is to use pre-commit hooks. Although they are called pre-commit, it is possible to run them on demand at any time.

You can find an example in these files: a list of hooks and a workflow file.