Fixes on messaging and calendar (#7485)

Fix syncedAt no longer been set on message sync.
Fix calendar data model:
- Add `syncedAt` to `CalendarChannelWorkspaceEntity`
- Move `recurringEventExternalId` from `CalendarEventWorkspaceEntity` to
`CalendarChannelEventAssociationWorkspaceEntity` since the id is
relative to one channel
Fix save queries on calendar sync after regression.

packages/twenty-server/src/modules/calendar/common/services/calendar-channel-sync-status.service.ts

@@ -171,6 +171,7 @@ export class CalendarChannelSyncStatusService {
       syncStatus: CalendarChannelSyncStatus.ACTIVE,
       throttleFailureCount: 0,
       syncStageStartedAt: null,
+      syncedAt: new Date().toISOString(),
     });
 
     await this.schedulePartialCalendarEventListFetch(calendarChannelIds);