reorganize headers

[Pistonight]

I tried clang-formatting all the code and suddenly got a wall of errors because the includes were sorted, so I figured it should be solved once for all

Generally headers/includes should be:

• self-contained: the header will work by including just the header, not have to include some other header before it
• minimal: the header should not include any file that the header doesn't directly need because it will force everyone who include it to also include those files.
• direct: for example if your header needs <cstdint>, then you should just include that instead of some other Foo.h that happens to include <cstdint>

Following these will make it less likely that when you change some header and something seemingly completed unrelated start breaking up, and builds will be faster because when you change some header there will be less stuff that needs recompiled

I did this manually with clangd's unused-include diagnostic and tested build works (and works when ported to my mod)

Another issue that exists is the include paths are kind of messy right now, for example SexyAppFramework headers can be included either like "Foo.h" or "SexyAppFramework/Foo.h" (since the include paths for sub-projects needs to be PUBLIC they just leak everywhere), and there are a bunch of "../../" includes. Ideally we only expose src in include paths and everyone should include like <Lawn/XXX.h> or <SexyAppFramework/XXX.h>