Use .hpp headers (#641)

[marioprats]

Cherry-pick moveit@3cd567e, with some conflict solving

[marioprats]

@sjahr Pre-commit is failing because it's unable to find clang-tidy-12, which seems unrelated to this PR. Has it worked before or do you normally bypass the check?

[marioprats]

I have reverted the change that switches to clang-format-14, because then some other issues show up
Looks like CI is just broken in this repo (it cant' find clang-format-12). We should check what upstream MTC is using these days and apply their updates, which probably requires merging their recent changes.
That can be a can of worms, so I think we should commit this change, and fix CI / merge upstream in a separate effort.