popups: :fixed => :static, major changes to popup API

+ New command: doom/popup-kill-all
+ Update references to :fixed (now named :static)
+ Simplified doom-popup-p; moved :static filtering to
  doom-popup-windows.
+ New :autofit popup property, which resizes the popup to fit its
  content, if possible.
+ doom-popup-windows now takes one boolean argument: whether to ignore
  static popups or not.

core/autoload/buffers.el

@@ -268,7 +268,7 @@ regex PATTERN. Returns the number of killed buffers."
 If PROJECT-P (universal argument), kill only buffers that belong to the current
 project."
   (interactive "P")
-  (doom/popup-close-all t)
+  (doom/popup-kill-all)
   (let ((buffers (if project-p (doom-project-buffer-list) (doom-buffer-list))))
     (mapc #'doom-kill-buffer-and-windows buffers)
     (unless (doom-real-buffer-p)