refactor: move common bindings as extension

Signed-off-by: Bart Jaskulski <bjaskulski@protonmail.com>

src/CommonBinding/I18n.php → src/Extension/CommonBinding/I18n.php

 <?php
 
-namespace WPDesk\Init\CommonBinding;
+namespace WPDesk\Init\Extension\CommonBinding;
 
 use WPDesk\Init\Binding\Hookable;
 use WPDesk\Init\Plugin\Plugin;

src/CommonBinding/RequirementsCheck.php → src/Extension/CommonBinding/RequirementsCheck.php

 <?php
 
-namespace WPDesk\Init\CommonBinding;
+namespace WPDesk\Init\Extension\CommonBinding;
 
 use WPDesk\Init\Binding\StoppableBinder;
 use WPDesk\Init\Configuration\Configuration;

src/Resources/bindings/index.php

 <?php
 
-use WPDesk\Init\CommonBinding\I18n;
-use WPDesk\Init\CommonBinding\RequirementsCheck;
+use WPDesk\Init\Extension\CommonBinding\I18n;
+use WPDesk\Init\Extension\CommonBinding\RequirementsCheck;
 
 return [
 	RequirementsCheck::class,

src/Resources/services.inc.php

 <?php
 
 use DI\Definition\Helper\AutowireDefinitionHelper;
-use WPDesk\Init\CommonBinding\I18n;
-use WPDesk\Init\CommonBinding\RequirementsCheck;
-/**
- * Define useful bindings for WordPress context.
- */
+use WPDesk\Init\Extension\CommonBinding\I18n;
+use WPDesk\Init\Extension\CommonBinding\RequirementsCheck;
 
 return [
 	wpdb::class              => static function () {