💥 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/completion/ivy/config.el

@@ -276,7 +276,7 @@ immediately runs it on the current candidate (ending the ivy session)."
 ;;
 ;; Evil key fixes
 
-(map! :when (featurep! :feature evil +everywhere)
+(map! :when (featurep! :editor evil +everywhere)
       :after ivy
       :map (ivy-occur-mode-map ivy-occur-grep-mode-map)
       :m "j"       #'ivy-occur-next-line