Add alerting http proxy option

[L3o-pold]

Fix #871

[codecov-io]

Codecov Report

Merging #872 (c2c6407) into main (cb24c74) will decrease coverage by 0.10%.
The diff coverage is 37.14%.

❗ Current head c2c6407 differs from pull request most recent head acd0006. Consider uploading reports for the commit acd0006 to get more accurate results

@@            Coverage Diff             @@
##             main     #872      +/-   ##
==========================================
- Coverage   56.68%   56.58%   -0.11%     
==========================================
  Files          67       67              
  Lines        5439     5463      +24     
==========================================
+ Hits         3083     3091       +8     
- Misses       1896     1910      +14     
- Partials      460      462       +2     

Impacted Files	Coverage Δ
pkg/notifier/factory.go	0.00% <0.00%> (ø)
pkg/notifier/client.go	31.42% <11.76%> (-21.21%)	⬇️
pkg/controller/events.go	55.65% <50.00%> (-0.60%)	⬇️
pkg/notifier/discord.go	72.22% <100.00%> (+0.79%)	⬆️
pkg/notifier/rocket.go	75.75% <100.00%> (+0.75%)	⬆️
pkg/notifier/slack.go	75.75% <100.00%> (+0.75%)	⬆️
pkg/notifier/teams.go	76.92% <100.00%> (+0.92%)	⬆️
pkg/canary/config_tracker.go	84.16% <0.00%> (+0.90%)	⬆️

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[stefanprodan]

@L3o-pold thank you for this! Can you confirm that this works with and without the proxy setting? Have you tested it with Slack or MS Teams?

[L3o-pold]

@stefanprodan I tested with and without proxy setting with Slack provider.

[stefanprodan]

LGTM

Thanks @L3o-pold 🏅