A CI job that use clang-format to check coding style issues in new
code has been added.
* kn/ci-clang-format:
ci/style-check: add `RemoveBracesLLVM` in CI job
check-whitespace: detect if no base_commit is provided
ci: run style check on GitHub and GitLab
clang-format: formalize some of the spacing rules
clang-format: avoid spacing around bitfield colon
clang-format: indent preprocessor directives after hash