fix(GODT-2326): Only run sync after addIMAPUser()

There is concurrency bug due to competing sync calls that can occur when
we clear the sync status in the Vault. Running sync at the end of
addIMAPUser() avoids the problem.

This patch also remove the execution of a sync task for
`user.ClearSyncStatus()`

internal/vault/user.go

@@ -197,6 +197,11 @@ func (user *User) RemFailedMessageID(messageID string) error {
 	})
 }
 
+// GetSyncStatus returns the user's sync status.
+func (user *User) GetSyncStatus() SyncStatus {
+	return user.vault.getUser(user.userID).SyncStatus
+}
+
 // ClearSyncStatus clears the user's sync status.
 func (user *User) ClearSyncStatus() error {
 	return user.vault.modUser(user.userID, func(data *UserData) {