MISC: copy .editorconfig, .clang-tidy, and .gitattributes from scummvm

[Die4Ever]

I know some of the .gitattributes rules don't affect this repo, but I think it's easier to keep the files in sync when they're completely identical and you don't have to worry about it

will need to squash merge cause I didn't do the commit message correctly lol, I was doing this to see if Github Actions would run