feat: add mainsail theme installer

scripts/ui/ms_theme_menu.sh

@@ -0,0 +1,33 @@
+ms_theme_ui(){
+  top_border
+  echo -e "|     ${red}~~~~~~~~ [ Mainsail Theme Installer ] ~~~~~~~${default}     | "
+  hr
+  echo -e "|  Please note:                                         | "
+  echo -e "|  Installing a theme from this menu will overwrite an  | "
+  echo -e "|  already installed theme or modified custom.css file! | "
+  hr
+  echo -e "|  Theme:                                               | "
+  echo -e "|  1) [Dracula]                                         | "
+  echo -e "|                                                       | "
+  echo -e "|  R) [Remove Theme]                                    | "
+  echo -e "|                                                       | "
+  quit_footer
+}
+
+ms_theme_menu(){
+  do_action "" "ms_theme_ui"
+  while true; do
+    read -p "${cyan}Perform action:${default} " action; echo
+    case "$action" in
+      1)
+        do_action "ms_theme_dracula" "ms_theme_ui";;
+      R|r)
+        do_action "ms_theme_delete" "ms_theme_ui";;
+      Q|q)
+        clear; advanced_menu; break;;
+      *)
+        deny_action "ms_theme_ui";;
+    esac
+  done
+  ms_theme_menu
+}