Add Dataset ID limit regex

Author: Ehesp

firestore-bigquery-export/extension.yaml

@@ -85,7 +85,7 @@ params:
     type: string
     label: Collection path
     description: >-
-      What is the path of the collection that you would like to export? 
+      What is the path of the collection that you would like to export?
       You may use `{wildcard}` notation to match a subcollection of all documents in a collection
       (for example: `chatrooms/{chatid}/posts`).
     default: posts
@@ -100,7 +100,7 @@ params:
     description: >-
       What ID would you like to use for your BigQuery dataset? This
       extension will create the dataset, if it doesn't already exist.
-    validationRegex: "^[a-zA-Z0-9_]+$"
+    validationRegex: "^[a-zA-Z0-9_]{1,1024}$"
     validationErrorMessage: >
       BigQuery dataset IDs must be alphanumeric (plus underscores) and must be no more than
       1024 characters.