External Notify added user info for file sync and support for sending notifications to Telegram topics (message_thread_id)

[ttrinh24]

Is your feature request related to a problem? Please describe.
External Notify enhancement: added user info on file synchronization, and support for targeting Telegram message threads (topics) when sending notifications.

Describe the solution you'd like
Add a form field to input message_thread_id for Telegram topic.
Add Username of the user performing file sync in notification messages

Describe alternatives you've considered
Curl test with query param message_thread_id successfully delivered to the corresponding topic

Additional context
Currently, External Notify Telegram sends messages without the acting Username and delivers them to the general topic.