💥 Remove :feature category

:feature was a "catch-all" category. Many of its modules fit better in
other categories, so they've been moved:

- feature/debugger -> tools/debugger
- feature/evil -> editor/evil
- feature/eval -> tools/eval
- feature/lookup -> tools/lookup
- feature/snippets -> editor/snippets
- feature/file-templates -> editor/file-templates
- feature/workspaces -> ui/workspaces

More potential changes in the future:

- A new :term category for terminal emulation modules (eshell, term and
  vterm).
- A new :os category for modules dedicated to os-specific functionality.
  The :tools macos module would fit here, but so would modules for nixos
  and arch.
- A new :services category for web-service integration, like wakatime,
  twitter, elfeed, gist and pastebin services.

modules/config/default/+emacs-bindings.el

@@ -105,7 +105,7 @@
       (:prefix ("q" . "quit/restart")
         :desc "Quit Emacs"                   "q" #'kill-emacs
         :desc "Save and quit Emacs"          "Q" #'save-buffers-kill-terminal
-        (:when (featurep! :feature workspaces)
+        (:when (featurep! :ui workspaces)
           :desc "Quit Emacs & forget session"  "X" #'+workspace/kill-session-and-quit)
         :desc "Restart & restore Emacs"      "r" #'doom/restart-and-restore
         :desc "Restart Emacs"                "R" #'doom/restart)