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/Services/PortalService.qml

@@ -117,7 +117,7 @@ Singleton {
 
     Timer {
         id: colorSchemeSettleTimer
-        interval: 1000
+        interval: 750
         onTriggered: {
             if (!root.canSyncColorScheme())
                 return;