Add new settings and cache repository files, update admin settings controller and templates

- Introduced new `SettingsRepository` and `CacheRepository` classes in the `autoload\Domain` namespace.
- Updated `SettingsController` in the `admin\Controllers` namespace to enhance settings management.
- Added new templates for settings in `admin\templates\settings` and `admin\templates\site`.
- Improved overall structure and organization of settings-related files.

admin/templates/site/main-layout.php

@@ -201,7 +201,7 @@
             </div>
           <? endif;?>
           <div class="row">
-            <div class="col-12 dashboard-page">
+            <div class="col-12 dashboard-page" id="content">
               <?= $this -> content;?>
             </div>
           </div>