GH-4362 Add syncing status (#4950)

This PR adds a `syncing` status on frontend.

Issue
- #4362

---------

Co-authored-by: Félix Malfait <felix.malfait@gmail.com>

packages/twenty-front/src/modules/accounts/types/MessageChannel.ts

@@ -6,4 +6,5 @@ export type MessageChannel = {
   isContactAutoCreationEnabled?: boolean;
   isSyncEnabled: boolean;
   visibility: InboxSettingsVisibilityValue;
+  syncStatus: string;
 };