feat(alerting): Overriding telegram id and token

[sbriskin]

Describe the feature request

Add support for overriding telegram recipients and bots. Something like this:

alerting:
  telegram:
    token: "NNNNNNNNN:xxxxxxx_yyyyyyyyy"
    id: "123456789"
    overrides:
      - group: "A"
        id: "-1009876543210"
      - group: "B"
        id: "-1001234567890"
        token: "NNNNNNNNN:aaaaaaaaa_bbbbbbbb"

Why do you personally want this feature to be implemented?

This is amazing app, but only one telegram id limit makes me cry.
I have a few telegram chats: one for devops team with their ci resources, one for QA with their test servers and one only for myself for other tasks. So I have to manually forward notifications from my personal chat to others. Please add override rules for telegram.

How long have you been using this project?

No response

Additional information

No response

[TwiN]

If anybody that wants to pick this up, here's 2 examples of the work needed: #272 #292

[lefes]

@TwiN Thank you for providing these examples. They were helpful for me in preparing the PR. I hope it passes your review. If needed, I will make any necessary fixes promptly and stay in touch.

[lefes]

@TwiN, I believe this issue can be closed. Would you agree?

[TwiN]

Yep, you're right @lefes!

Resolved by #826