Re-enable doom-modeline in treemacs

The current `doom-modeline` shows the current workspace name in `treemacs` since Alexander-Miller/treemacs#1049, thus making the `doom-modeline` useful again.

extensions/doom-themes-ext-treemacs.el

@@ -86,9 +86,6 @@ Only takes effect if `doom-themes-treemacs-enable-variable-pitch' is non-nil."
   "Set `line-spacing' in treemacs buffers."
   (setq line-spacing doom-themes-treemacs-line-spacing))
 
-(defun doom-themes-hide-modeline ()
-  (setq mode-line-format nil))
-
 (defun doom-themes-enable-treemacs-variable-pitch-labels (&rest _)
   (when doom-themes-treemacs-enable-variable-pitch
     (dolist (face '(treemacs-root-face
@@ -129,9 +126,6 @@ Only takes effect if `doom-themes-treemacs-enable-variable-pitch' is non-nil."
   ;; Fix #293: tabs messing up formatting in `treemacs-icons-dired-mode'
   (add-hook 'treemacs-icons-dired-mode-hook #'doom-themes-fix-treemacs-icons-dired-mode)
 
-  ;; The modeline isn't useful in treemacs
-  (add-hook 'treemacs-mode-hook #'doom-themes-hide-modeline)
-
   ;; Disable fringes (and reset them everytime treemacs is selected because it
   ;; may change due to outside factors)
   (add-hook 'treemacs-mode-hook #'doom-themes-hide-fringes-maybe)