Introduce autodefs to replace some settings

+ :popup -> set-popup-rule!
+ :popups -> set-popup-rules!
+ :company-backend -> set-company-backend!
+ :evil-state -> set-evil-initial-state!

I am slowly phasing out the setting system (def-setting! and set!),
starting with these.

What are autodefs? These are functions that are always defined, whether
or not their respective modules are enabled. However, when their modules
are disabled, they are replaced with macros that no-op and don't
waste time evaluating their arguments.

The old set! function will still work, for a while.

modules/lang/scala/config.el

@@ -12,7 +12,7 @@
         ;; let DOOM handle company setup
         ensime-completion-style nil)
 
-  (set! :company-backend 'scala-mode '(ensime-company company-yasnippet))
+  (set-company-backend! 'scala-mode '(ensime-company company-yasnippet))
 
   ;; Fix void-variable imenu-auto-rescan error caused by `ensime--setup-imenu'
   ;; trying to make imenu variables buffer local before imenu is loaded.