Yellow squiggly lines begone!
Done automatically on .cpp files through `run-clang-tidy`, with manual corrections to the mistakes.
If an import is directly used, but is technically unnecessary since it's recursively imported by something else, it is *not* removed.
The tool doesn't touch .h files, so I did some of them by hand while fixing errors due to old recursive imports.
Not everything is removed, but the cleanup should be substantial enough.
Because this done on Linux, code that isn't used on it is mostly untouched.
(Hopefully no open PR is depending on these imports...)

DolphinTool: Use {fmt} library

New dolphin-tool command: "header"
-b / --block_size
-c / --compression
-l / --compression_level

Informative RVZ/WIA header2 value "compression_level" is now a s32 instead of a u32, because negative compression is a thing.

Speaking of, it is now possible to use negative compression levels in dolphin-tool's convert command (not the GUI, though).