Call AccessibilityManager.startFlashNotificationEvent method in...

Call AccessibilityManager.startFlashNotificationEvent method in NotificationManagerService to implement Flash Notification for Notification.

Bug: 237628564
Test: atest BuzzBeepBlinkTest
Change-Id: Ib790ceaa0d181ba9ab0654ab09e34da819350d26
Signed-off-by: yw.bae <yw.bae@samsung.corp-partner.google.com>
Signed-off-by: Angela Wang <angelala@google.com>