Description
I want to suggest a feature to add chat_id_file Telegram configuration parameter to provide more securely pass chat_id like already existing bot_token_file.

Problem
Now I have to pass chat_id in cleartext inside config file and it's not safe.
This feature allow to pass file contains chat_id value using secrets or volumes sections in docker-compose.

How to solve
Add receivers['telegram']/telegram_configs/chat_id_file field with type string.
Field chat_id_file must take a path to file with chat_id.

I've already implemented it locally and I'm ready to contribute it.