Introduce functions for interacting with library panels API (#30993)

public/app/features/library-panels/state/api.ts

+import { getBackendSrv } from 'app/core/services/backend_srv';
+
+export interface LibraryPanelDTO {
+  id: number;
+  orgId: number;
+  folderId: number;
+  uid: string;
+  name: string;
+  model: any;
+  meta: LibraryPanelDTOMeta;
+}
+
+export interface LibraryPanelDTOMeta {
+  canEdit: boolean;
+  created: string;
+  updated: string;
+  createdBy: LibraryPanelDTOMetaUser;
+  updatedBy: LibraryPanelDTOMetaUser;
+}
+
+export interface LibraryPanelDTOMetaUser {
+  id: number;
+  name: string;
+  avatarUrl: string;
+}
+
+export async function getLibraryPanels(): Promise<LibraryPanelDTO[]> {
+  const { result } = await getBackendSrv().get(`/api/library-panels`);
+  return result;
+}
+
+export async function addLibraryPanel(panelSaveModel: any, folderId: number): Promise<LibraryPanelDTO> {
+  const { result } = await getBackendSrv().post(`/api/library-panels`, {
+    folderId,
+    name: panelSaveModel.title,
+    model: panelSaveModel,
+  });
+  return result;
+}
+
+export async function updateLibraryPanel(panelSaveModel: any, folderId: number): Promise<LibraryPanelDTO> {
+  const { result } = await getBackendSrv().patch(`/api/library-panels/${panelSaveModel.libraryPanel.uid}`, {
+    folderId,
+    name: panelSaveModel.title,
+    model: panelSaveModel,
+  });
+  return result;
+}
+
+export function deleteLibraryPanel(uid: string): Promise<{ message: string }> {
+  return getBackendSrv().delete(`/api/library-panels/${uid}`);
+}
+
+export async function getLibraryPanelConnectedDashboards(libraryPanelUid: string): Promise<number[]> {
+  const { result } = await getBackendSrv().get(`/api/library-panels/${libraryPanelUid}/dashboards`);
+  return result;
+}