feat: Control the allowed login methods via Super Admin (#12892)

- Control the allowed authentication methods for a chatwoot installation
via super admin configs. [SAML, Google Auth etc]
------
[Codex
Task](https://chatgpt.com/codex/tasks/task_e_6917d503b6e48326a261672c1de91462)

---------

Co-authored-by: Pranav <pranav@chatwoot.com>
Co-authored-by: Sivin Varghese <64252451+iamsivin@users.noreply.github.com>

app/controllers/super_admin/app_configs_controller.rb

@@ -15,14 +15,20 @@ class SuperAdmin::AppConfigsController < SuperAdmin::ApplicationController
   end
 
   def create
+    errors = []
     params['app_config'].each do |key, value|
       next unless @allowed_configs.include?(key)
 
       i = InstallationConfig.where(name: key).first_or_create(value: value, locked: false)
       i.value = value
-      i.save!
+      errors.concat(i.errors.full_messages) unless i.save
+    end
+
+    if errors.any?
+      redirect_to super_admin_app_config_path(config: @config), alert: errors.join(', ')
+    else
+      redirect_to super_admin_settings_path, notice: "App Configs - #{@config.titleize} updated successfully"
     end
-    redirect_to super_admin_settings_path, notice: "App Configs - #{@config.titleize} updated successfully"
   end
 
   private
@@ -42,7 +48,7 @@ class SuperAdmin::AppConfigsController < SuperAdmin::ApplicationController
       'instagram' => %w[INSTAGRAM_APP_ID INSTAGRAM_APP_SECRET INSTAGRAM_VERIFY_TOKEN INSTAGRAM_API_VERSION ENABLE_INSTAGRAM_CHANNEL_HUMAN_AGENT],
       'whatsapp_embedded' => %w[WHATSAPP_APP_ID WHATSAPP_APP_SECRET WHATSAPP_CONFIGURATION_ID WHATSAPP_API_VERSION],
       'notion' => %w[NOTION_CLIENT_ID NOTION_CLIENT_SECRET],
-      'google' => %w[GOOGLE_OAUTH_CLIENT_ID GOOGLE_OAUTH_CLIENT_SECRET GOOGLE_OAUTH_REDIRECT_URI]
+      'google' => %w[GOOGLE_OAUTH_CLIENT_ID GOOGLE_OAUTH_CLIENT_SECRET GOOGLE_OAUTH_REDIRECT_URI ENABLE_GOOGLE_OAUTH_LOGIN]
     }
 
     @allowed_configs = mapping.fetch(