feat: Expose databaseId and projectId getter on Firestore class (#1937)

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Fixes #1936

dev/src/index.ts

@@ -773,9 +773,6 @@ export class Firestore implements firestore.Firestore {
 
   /**
    * Returns the Database ID for this Firestore instance.
-   *
-   * @private
-   * @internal
    */
   get databaseId(): string {
     return this._databaseId || DEFAULT_DATABASE_ID;