Add extensions to system configs

- Add extension entry to configs
- Expose extensions list config on the api
- Allow extensions to be configured in extension folder

config/core_services.yaml

@@ -35,6 +35,7 @@ services:
       $recordViewActionLimits: '%module.recordview.actions_limits%'
       $groupedFieldsTypeMap: '%record.fields.grouped_fields_type_map%'
       $uiConfigs: '%ui%'
+      $extensions: '%extensions%'
   _instanceof:
     App\Process\Service\ProcessHandlerInterface:
       tags: [ 'app.process.handler' ]

config/services/legacy/exposed_system_configs.yaml

@@ -25,3 +25,4 @@ parameters:
     module_routing: true
     recordview_actions_limits: true
     ui: true
+    extensions: true

core/backend/SystemConfig/LegacyHandler/SystemConfigHandler.php

@@ -83,6 +83,8 @@ class SystemConfigHandler extends LegacyHandler implements SystemConfigProviderI
      * @param array $listViewActionsLimits
      * @param array $recordViewActionLimits
      * @param array $uiConfigs
+     * @param array $extensions
+     * @param SessionInterface $session
      */
     public function __construct(
         string $projectDir,
@@ -104,6 +106,7 @@ class SystemConfigHandler extends LegacyHandler implements SystemConfigProviderI
         array $listViewActionsLimits,
         array $recordViewActionLimits,
         array $uiConfigs,
+        array $extensions,
         SessionInterface $session
     )
     {
@@ -121,6 +124,7 @@ class SystemConfigHandler extends LegacyHandler implements SystemConfigProviderI
         $this->injectedSystemConfigs['listview_actions_limits'] = $listViewActionsLimits;
         $this->injectedSystemConfigs['recordview_actions_limits'] = $recordViewActionLimits;
         $this->injectedSystemConfigs['ui'] = $uiConfigs;
+        $this->injectedSystemConfigs['extensions'] = $extensions;
         $this->mappers = $mappers;
         $this->systemConfigKeyMap = $systemConfigKeyMap;
     }