This MR is the continuation of the discussion at !4192 (merged).
It enables clang-format for
winsys/radeon and adds a simple check in CI to verify the code style used matches the one defined in
WIP for various reasons:
- we don't know if we want to use clang-format yet
- the CI check is incomplete (maybe it should be a separate
linterstage, running before any build starts)