feat(Themes): add support for GTK3 dynamic theming (#2523)

* feat(Themes): add support for GTK3 dynamic theming

Instead of overriding named colors of all GTK3 themes via the config
directory file, only override named colors for each variant of the
adw-gtk3 theme (light and dark), and let GTK3 apps change themes
depending on the value of org.gnome.desktop.interface color-scheme.

* fix(Themes): apply requested changes

- remove gtk3 override if it's a symlink
- remove call to gtk.sh with old arg 'assets-only'
- append key to dconf path to respect dconf write signature

* refactor(Themes): separate 'include'/'apply' logic for GTK3 dynamic theming

* revert(Themes): reset timer between color-scheme refresh

- rename DMS_ENABLE_GTK4_REFRESH to DMS_ENABLE_GTK_REFRESH
- revert a3fba8

* feat(Themes): add 'remove' mode to gtk.sh

Allow to remove all inclusions and overrides for GTK.

* fix(Themes): backup adw-gtk3 original css in 'apply' (not 'include')

* style(Themes): rename argument 'include' to 'patch' for clarity

quickshell/matugen/templates/gtk-colors.css

@@ -1,3 +1,5 @@
+/* BEGIN DMS OVERRIDE */
+
 /*
 * GTK Colors
 * Generated with Matugen
@@ -46,3 +48,5 @@ a color between surface and surface container so I think just giving this surfac
 @define-color theme_unfocused_base_color @window_bg_color;
 @define-color theme_unfocused_selected_bg_color @accent_bg_color;
 @define-color theme_unfocused_selected_fg_color @accent_fg_color;
+
+/* END DMS OVERRIDE */

quickshell/matugen/templates/gtk-light-colors.css

@@ -1,3 +1,5 @@
+/* BEGIN DMS OVERRIDE */
+
 /*
 * GTK Colors
 * Generated with Matugen
@@ -7820,3 +7822,5 @@ window.background:not(.solid-csd):not(.csd) > notebook > stack:not(:only-child)
 @define-color sidebar_fg_color @window_fg_color;
 @define-color sidebar_border_color @window_bg_color;
 @define-color sidebar_backdrop_color @window_bg_color;
+
+/* END DMS OVERRIDE */