Added unread message count badge on the Jump to bottom button (#131)

[alanpoon]

Screen.Recording.2024-10-10.233052.mp4

• [ x ] Scroll to the most recent message
• Jump to the first unread message

Solution to solve this issue JTB

Logic added:

1. whenever there is new timeline item, check for number of unread message and draw accordingly onto the unread_notification_badge.
2. Whenever sending fully read receipt, clear the content unread_notification_badge.

[alanpoon]

Doing a combine PR ticket with other ticket
#206