module!: add :editor whitespace

BREAKING CHANGE: Moves ws-butler, dtrt-indent, and whitespace defaults
out of Doom's core and into a new module. ws-butler is gated behind
+trim and dtrt-indent behind +guess. Users who depend on/like these
packages will need to enable the new module and their respective
flags (which is the default going forward).

This change is motivated by an ongoing effort to slim down Doom's
core (by (re)moving non-essentials from it).

This also addresses an issue where dtrt-indent would vastly increase
load times for some major-modes (e.g. elixir-mode & elm-mode, see #7537)
by restricting it to non-project files and non-read-only buffers AND
excludign those two major modes from indent guessing.

Fix: #8516
Fix: #7537

modules/editor/word-wrap/autoload.el

@@ -64,14 +64,15 @@ wrapped at `fill-column' by configuring `+word-wrap-fill-style'."
               (eq +word-wrap-fill-style 'soft)))
 
         (unless +word-wrap--major-mode-is-visual
-          (require 'dtrt-indent) ; for dtrt-indent--search-hook-mapping
-          (setq-local +word-wrap--major-mode-indent-var
-                      (let ((indent-var (caddr (dtrt-indent--search-hook-mapping major-mode))))
-                        (if (listp indent-var)
-                            (car indent-var)
-                          indent-var)))
-
-          (advice-add #'adaptive-wrap-fill-context-prefix :around #'+word-wrap--adjust-extra-indent-a))
+          (when (require 'dtrt-indent nil t)
+            ;; for dtrt-indent--search-hook-mapping
+            ;; TODO: Generalize this?
+            (setq-local +word-wrap--major-mode-indent-var
+                        (let ((indent-var (caddr (dtrt-indent--search-hook-mapping major-mode))))
+                          (if (listp indent-var)
+                              (car indent-var)
+                            indent-var)))
+            (advice-add #'adaptive-wrap-fill-context-prefix :around #'+word-wrap--adjust-extra-indent-a)))
 
         (when +word-wrap--enable-adaptive-wrap-mode
           (adaptive-wrap-prefix-mode +1))