FEATURE: display commit hash for each plugin on /admin/plugins page. (#22176)

It will help to find out the current version of the plugins even without the `docker_manager` plugin.

app/serializers/admin_plugin_serializer.rb

@@ -10,7 +10,9 @@ class AdminPluginSerializer < ApplicationSerializer
              :enabled,
              :enabled_setting,
              :has_settings,
-             :is_official
+             :is_official,
+             :commit_hash,
+             :commit_url
 
   def id
     object.directory_name
@@ -68,4 +70,12 @@ class AdminPluginSerializer < ApplicationSerializer
   def is_official
     Plugin::Metadata::OFFICIAL_PLUGINS.include?(object.name)
   end
+
+  def commit_hash
+    object.commit_hash
+  end
+
+  def commit_url
+    object.commit_url
+  end
 end