feat(icons): use nerd-fonts to display icons in terminals

Uses the new nerd-icons package to display icons in various places
similar to all-the-icons. But it works in a terminal too as long as the
terminal is using a Nerd Font.

modules/projects/siren-treemacs.el

@@ -61,9 +61,6 @@
   (treemacs-define-RET-action
    'file-node-closed #'treemacs-visit-node-in-most-recently-used-window))
 
-(use-package treemacs-all-the-icons
-  :after (treemacs))
-
 (use-package treemacs-projectile
   :after (treemacs projectile)
   :custom