Add Billing Permissions (#16364)

* add billing permissions

* update store.go

* Update permission.go

Co-authored-by: Mattermod <mattermod@users.noreply.github.com>

model/migration.go

@@ -22,6 +22,7 @@ const (
 	MIGRATION_KEY_SIDEBAR_CATEGORIES_PHASE_2                  = "migration_sidebar_categories_phase_2"
 	MIGRATION_KEY_ADD_CONVERT_CHANNEL_PERMISSIONS             = "add_convert_channel_permissions"
 	MIGRATION_KEY_ADD_SYSTEM_ROLES_PERMISSIONS                = "add_system_roles_permissions"
+	MIGRATION_KEY_ADD_BILLING_PERMISSIONS                     = "add_billing_permissions"
 	MIGRATION_KEY_ADD_MANAGE_SHARED_CHANNEL_PERMISSIONS       = "manage_shared_channel_permissions"
 	MIGRATION_KEY_ADD_MANAGE_REMOTE_CLUSTERS_PERMISSIONS      = "manage_remote_clusters_permissions"
 )