Duplicate .clang-format file in OpenFOAM cases

[MakisH]

While we have a central .clang-format file for the tutorials, we also have such a file for the OpenFOAM solver in the partitioned heat conduction case. We need this mainly because the default format moves around header inclusions, which breaks OpenFOAM code (we need to set SortIncludes: false). This is already a duplicate of the file used in the OpenFOAM adapter, and other PRs are introducing more duplication (such as #551).

We could maybe move the OpenFOAM-specific file to tools/ for now, and link to it from the various directories.

Note that we are also working on a community proposal, which we could maybe one day import.

[fsimonis]

A possibility which works in pre-commit but not IDEs is to define 2 clang-format hooks and explicitly pass the configuration file to format the OpenFOAM solvers. This way we could use a single clang format file for all openfoam solvers in the repo.

https://github.com/pre-commit/mirrors-clang-format/blob/7d85583be209cb547946c82fbe51f4bc5dd1d017/.pre-commit-hooks.yaml#L7

https://clang.llvm.org/docs/ClangFormatStyleOptions.html#configuring-style-with-clang-format

[MakisH]

I like the idea. If we also distribute the file as a separate repository, we could import it as a git submodule (I will eventually do this in the context of the OpenFOAM SIG RSE).

[fsimonis]

I like the idea.

I'll try it in #551 and link to the existing clang format in on of the openfoam solver directories.