feat(config)!: Improve config module resolution

The new system is slightly less flexible, but the code and lua
definitions is now a lot simpler and easier to understand.
In fact the old lua definition was not actually correct.

It is likely that existing configs require not/minimal tweaks to work
again.

config/rooms.lua

@@ -1,4 +1,4 @@
---- @type SetupTable
+--- @type Module
 return {
 	require("config.rooms.bathroom"),
 	require("config.rooms.bedroom"),