feat: add cloud events support

[thisthat]

This PR

• adds an optional new entry in the KeptnConfig to configure the CE endpoint
• adds a CloudEvent emitter
• register by default both K8s and CE as destination of events

Parts of #1841

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[codecov]

Codecov Report

Merging #1843 (2c9af46) into main (adf4621) will increase coverage by 0.03%.
Report is 1 commits behind head on main.
The diff coverage is 81.96%.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1843      +/-   ##
==========================================
+ Coverage   83.38%   83.41%   +0.03%     
==========================================
  Files         134      135       +1     
  Lines        8288     8346      +58     
==========================================
+ Hits         6911     6962      +51     
- Misses       1121     1127       +6     
- Partials      256      257       +1     

Files Changed	Coverage Δ
...cycle-operator/controllers/common/config/config.go	69.23% <0.00%> (-30.77%)	⬇️
...fecycle-operator/controllers/common/eventsender.go	88.70% <87.71%> (-11.30%)	⬇️

... and 3 files with indirect coverage changes

Flag	Coverage Δ
certificate-operator	68.55% <ø> (ø)
lifecycle-operator	84.88% <81.96%> (-0.05%)	⬇️
metrics-operator	82.92% <ø> (+0.02%)	⬆️
scheduler	32.12% <ø> (ø)

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[sonarcloud]

Kudos, SonarCloud Quality Gate passed!   

0 Bugs
0 Vulnerabilities
0 Security Hotspots
0 Code Smells

No Coverage information
0.1% Duplication