Make it possible to use this action to run custom `clang-format` invocations

[zyv]

Hey there,

You've done a fantastic job providing all possible clang-format versions. However, at the moment the action insists on running clang-format itself.

It would be very nice if you could add a mode for it to behave more like setup-* actions, so that the requested clang-format is just put in the $PATH and it's our job to run it the way we want.

- uses: jidicula/clang-format-action@v4
  with:
    clang-format-version: '13'
    setup-only: true

The reason I think this is desirable is that we have clang-format built into our build system (make indent) and I don't want to replicate that in your action settings.

However, setting up clang-format is challenging (as I'm sure you'll agree), so it would be great if I could reuse your work for our purposes.

Thanks a lot, Yury