feat(Gmail Node): Add thread option for draft emails (#8729)

Co-authored-by: Jonathan Bennetts <jonathan.bennetts@gmail.com>

packages/nodes-base/nodes/Google/Gmail/v2/DraftDescription.ts

@@ -151,6 +151,14 @@ export const draftFields: INodeProperties[] = [
 				default: '',
 				description: 'The email address that the reply message is sent to',
 			},
+			{
+				displayName: 'Thread ID',
+				name: 'threadId',
+				type: 'string',
+				placeholder: '18cc573e2431878f',
+				default: '',
+				description: 'The identifier of the thread to attach the draft',
+			},
 			{
 				displayName: 'Attachments',
 				name: 'attachmentsUi',