refactor!: restructure Doom core

BREAKING CHANGE: This restructures Doom's core in an effort to slim it
down and partially mirror architectural changes coming in v3. This is
part 2 of 3 commits (part 1 being 1590434), done to facilitate a change
in part 3 that will introduce a new `doom!` syntax for pulling
third-party module libraries from remote sources (similar to `package!`
statements). I am backporting this from V3 so I can move our modules out
into separate repos sooner than later, so development on modules can
continue separately without interfering with v3's roll out.

Though this is labeled a breaking change, it shouldn't affect most users
except those few tinkering directly with Doom's internals.

Ref: 15904349cf

lisp/cli/profiles.el

@@ -69,15 +69,9 @@
               (dolist (p removed) (print! (item "Removed %S") (car p)))
               (dolist (p changed) (print! (item "Changed %S") (car p)))
               (doom-file-write doom-cli-known-profiles-file (list new-profiles) :mode #o600)
-              (doom-profiles-save new-profiles load-file)
+              (doom-profiles-write-load-file new-profiles load-file)
               (print! (success "Regenerated profile loader: %s")
                       (path load-file)))))))))
 
-
-;;
-;;; Helpers
-
-
-
 (provide 'doom-cli-profiles)
 ;;; profiles.el ends here