Dashboard: Support Angular panel migrations in v2 schema (#115368)

* V2: Support angular panel migrations

* Add autoMigrateFrom and update ensureV2

* Remove context files

* Simplify angular migration handler

* linter

* Only include angular options in angular panel data

packages/grafana-schema/src/raw/dashboard/x/dashboard_types.gen.ts

@@ -838,6 +838,11 @@ export const defaultDashboardCursorSync: DashboardCursorSync = DashboardCursorSy
  * Dashboard panels are the basic visualization building blocks.
  */
 export interface Panel {
+  /**
+   * When a panel is migrated from a previous version (Angular to React), this field is set to the original panel type.
+   * This is used to determine the original panel type when migrating to a new version so the plugin migration can be applied.
+   */
+  autoMigrateFrom?: string;
   /**
    * Sets panel queries cache timeout.
    */