[Core] Add multiple/external cog paths support (#853)

* WIP cog path manager

* Initial working state

* Get real reloading working

* Type error thingy

* And fix the tests

* Start UI shit

* path reordering

* Add install path getter/setter and fix config syntax

* Determine bot directory at runtime

* Add UI commands for install path

* Update downloader to use install path

* Add sane install path default

* Make evaluation of cog install path lazy

* Some typing fixes

* Add another line to codeowners

* Conditionally put install path in paths

* Always put install path first

* Dont allow people to add the installdir as an additional path, guarantee install dir isn't shown with paths command

* Make shit update loaded cogs

* Add tests

* Another one

.github/CODEOWNERS

@@ -3,6 +3,7 @@
 
 # Core
 core/config.py              @tekulvw
+core/cog_manager.py         @tekulvw
 core/drivers/*              @tekulvw
 core/sentry_setup.py        @Kowlin @tekulvw