notify_telegram plugin

[YanikusGG]

This is initial implementation for notify_telegram plugin. Later I will create PR for collectd 6 also.

The notify_telegram plugin uses libcurl and Telegram Bot API to send notifications to a configured telegram users.
It also can send config instruction with ChatID in response to all users by long polling or webhooks using libcurl, libyajl, libmicrohttpd.

ChangeLog: Introduce notify_telegram plugin

Reference: https://core.telegram.org/bots/api

[eero-t]

This is initial implementation for notify_telegram plugin. Later I will create PR for collectd 6 also.

New plugins should go to collectd-6.0 branch, only existing plugins are updated in v5.x code (main) , but please handle review feedback first.

[YanikusGG]

This is initial implementation for notify_telegram plugin. Later I will create PR for collectd 6 also.

New plugins should go to collectd-6.0 branch, only existing plugins are updated in v5.x code (main) , but please handle review feedback first.

Thank you for your helpful issues. I've fixed most of them.

[eero-t]

Thanks, fixes look good! Next step is review from Florian (@octo) for the v6 version of the PR.

(He hasn't been active for a while, but hopefully you don't need to wait too long...)