feat: add support for sending webhook events

[shini4i]

Closes #256, potentially can partly cover #131

[codecov]

Codecov Report

Attention: Patch coverage is 57.14286% with 24 lines in your changes are missing coverage. Please review.

Project coverage is 51.23%. Comparing base (87b56d7) to head (05b0bc4).

Files	Patch %	Lines
cmd/argo-watcher/notifications/webhook.go	60.52%	10 Missing and 5 partials ⚠️
cmd/argo-watcher/argocd/argo_status_updater.go	52.94%	5 Missing and 3 partials ⚠️
cmd/argo-watcher/server/server.go	0.00%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #271      +/-   ##
==========================================
+ Coverage   50.99%   51.23%   +0.23%     
==========================================
  Files          25       26       +1     
  Lines        1653     1702      +49     
==========================================
+ Hits          843      872      +29     
- Misses        737      751      +14     
- Partials       73       79       +6     

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[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
No data about Coverage
0.0% Duplication on New Code

See analysis details on SonarCloud