feat: allow promise in EntityPresentationApi for all the asynchronous processes working under the hood

Signed-off-by: NIKUNJ LALITKUMAR HUDKA <nikunjhudka123@gmail.com>

plugins/catalog-react/src/apis/EntityPresentationApi/EntityPresentationApi.ts

@@ -109,6 +109,11 @@ export interface EntityRefPresentation {
    * elsewhere.
    */
   update$?: Observable<EntityRefPresentationSnapshot>;
+
+  /* The `promise` property in the `EntityRefPresentation` interface is defining a property named
+  `promise` that holds a promise. This promise resolves to an array of
+  `EntityRefPresentationSnapshot` objects. */
+  promise: Promise<EntityRefPresentationSnapshot[]>;
 }
 
 /**

plugins/catalog/src/apis/EntityPresentationApi/DefaultEntityPresentationApi.ts

@@ -298,10 +298,37 @@ export class DefaultEntityPresentationApi implements EntityPresentationApi {
           };
         });
 
-    return {
+    const entityRefPresentation: EntityRefPresentation = {
       snapshot: initialSnapshot,
       update$: observable,
+      get promise() {
+        return new Promise<EntityRefPresentationSnapshot[]>(
+          (resolve, reject) => {
+            if (!observable) {
+              resolve([initialSnapshot]);
+            } else {
+              const res: EntityRefPresentationSnapshot[] = [];
+              const subscription = observable.subscribe({
+                next: snapshot => {
+                  res.push(snapshot);
+                },
+                error: error => {
+                  initialSnapshot = {
+                    primaryTitle: entityRef,
+                    entityRef: entityRef,
+                  };
+                },
+                complete() {
+                  subscription.unsubscribe();
+                  resolve(res);
+                },
+              });
+            }
+          },
+        );
+      },
     };
+    return entityRefPresentation;
   }
 
   #getEntityForInitialRender(entityOrRef: Entity | string): {