💥 Replace core-popup with new feature/popup module

This is a breaking change! Update your :popup settings. Old ones will
throw errors!

Doom's new popup management system casts off its shackles (hur hur) and
replaces them with the monster that is `display-buffer-alist`, and
window parameters.

However, this is highly experimental! Expect edge cases.  Particularly
with org-mode and magit (or anything that does its own window
management).

Relevant to #261, #263, #325

modules/lang/rest/config.el

@@ -4,7 +4,7 @@
   :commands restclient-mode
   :mode ("\\.http$" . restclient-mode)
   :config
-  (set! :popup "*HTTP Response*" :size 30 :select t :noesc t :autokill t)
+  (set! :popup "^\\*HTTP Response" '((size . 0.4)) '((escape-quit . other)))
   (map! :mode restclient-mode
         :n [M-return] 'restclient-http-send-current
         :localleader