💥 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/nav-flash/config.el

@@ -5,7 +5,7 @@
     +org/dwim-at-point org-find-file org-find-file-at-mouse)
   "A list of commands that should not trigger nav-flash.")
 
-(def-package! nav-flash
+(use-package! nav-flash
   :defer t
   :init
   ;; NOTE In :tools lookup `recenter' is hooked to a bunch of jumping