Add HTTP_PROXY to telegram provider

[gioppoluca]

Seems that there is not support for HTTP_PROXY.
It should be possible to use the NewBotWithClient API instead of only NewBot.
Also the chart and other parts should be updated but it could help those that are behing a proxy.

[Khodesaeed]

I need this feature too.

[marcelcorso]

@Khodesaeed and @gioppoluca don't you guys want to go on a Golang adventure and send in a PR? 🤣 😅

[Khodesaeed]

Sure... @marcelcorso :))