💥 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/editor/parinfer/config.el

@@ -8,7 +8,7 @@
           pretty-parens
           smart-tab
           smart-yank))
-  (when (featurep! :feature evil +everywhere)
+  (when (featurep! :editor evil +everywhere)
     (push 'evil parinfer-extensions))
   :config
   (map! :map parinfer-mode-map

modules/editor/parinfer/packages.el

@@ -1,7 +1,7 @@
 ;; -*- no-byte-compile: t; -*-
 ;;; editor/parinfer/packages.el
 
-(when (featurep! :feature evil)
+(when (featurep! :editor evil)
   ;; Parinfer uses `evil-define-key' without loading evil, so if evil is
   ;; installed *after* parinfer, parinfer will throw up void-function errors.
   ;; because evil-define-key (a macro) wasn't expanded at compile-time. So we