💥 Rename def-package! -> use-package!

Calling this pivotal macro "def-package!" has frequently been a source
of confusion. It is a thin wrapper around use-package, and it should be
obvious that it is so. For this reason, and to match the naming
convention used with other convenience macros/wrappers, it is now
use-package!.

Also changes def-package-hook! -> use-package-hook!

The old macros are now marked obsolete and will be removed when straight
integration is merged.

modules/ui/deft/config.el

@@ -1,6 +1,6 @@
 ;;; ui/deft/config.el -*- lexical-binding: t; -*-
 
-(def-package! deft
+(use-package! deft
   :commands deft
   :init
   (setq deft-extensions '("org" "md" "tex" "txt")