ongoing clean up and organization work

[magiruuvelvet]

• hooks/*
• package.accept_keywords/*
• env/* - still contains obsolete and outdated stuff from the LLVM 9.x and 11.x era
• package.env/* - organize, clean up gnu-extensions and rust stuff
• package.mask/* - notes: dev-lang, tmp
• package.use/* - planned dbus and systemd reduction
• patches/*
• profile/* - contains some obsolete stuff, and requires some general maintenance
• /