[Code style] Consider using clang-format on all thprac (non-3rdParty) code

[Lmocinemod]

Currently, the codebase does not conform to any single formatting convention. There does exist a .clang-format file in the project root, but it does not seem to be used.

I've created an experimental branch on my fork - which is not intended to be merged - to explore possible formatting options. Currently, the formatting rules in use there are completely ridiculous (featuring a column limit of 180, etc.), as I curated them to produce the smallest possible diff (through manual trial and error - a smaller diff may still be possible).

I'm creating this issue to facilitate discussion, as formatting conventions are highly subjective.