RBAC: allow listing permissions on the root folder (#82184)

* allow returning AC metadata for the root folder

* add a test

* share the reserved root folder UID with frontend

packages/grafana-data/src/types/config.ts

@@ -225,6 +225,7 @@ export interface GrafanaConfig {
   rudderstackIntegrationsUrl: string | undefined;
   sqlConnectionLimits: SqlConnectionLimits;
   sharedWithMeFolderUID?: string;
+  rootFolderUID?: string;
 
   // The namespace to use for kubernetes apiserver requests
   namespace: string;

packages/grafana-runtime/src/config.ts

@@ -167,6 +167,7 @@ export class GrafanaBootConfig implements GrafanaConfig {
   tokenExpirationDayLimit: undefined;
   disableFrontendSandboxForPlugins: string[] = [];
   sharedWithMeFolderUID: string | undefined;
+  rootFolderUID: string | undefined;
 
   constructor(options: GrafanaBootConfig) {
     this.bootData = options.bootData;