chore: add maturity status for each feature

[thisthat]

This PR wants to provide more visibility on the new feature we're adding and their current maturity level.

[codecov]

Codecov Report

Merging #825 (e442638) into main (fa3e73c) will increase coverage by 0.63%.
The diff coverage is n/a.

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #825      +/-   ##
==========================================
+ Coverage   57.91%   58.55%   +0.63%     
==========================================
  Files          89       97       +8     
  Lines        7072     7552     +480     
==========================================
+ Hits         4096     4422     +326     
- Misses       2825     2938     +113     
- Partials      151      192      +41     

Impacted Files	Coverage Δ
...lers/lifecycle/keptnworkloadinstance/controller.go	81.16% <0.00%> (-0.45%)	⬇️
...llers/keptnwebhookcontroller/certificate_secret.go	85.88% <0.00%> (ø)
klt-cert-manager/kubeutils/secret.go	67.39% <0.00%> (ø)
...okcontroller/keptnwebhookcertificate_controller.go	52.00% <0.00%> (ø)
...anager/controllers/keptnwebhookcontroller/certs.go	70.96% <0.00%> (ø)
klt-cert-manager/eventfilter/eventfilter.go	100.00% <0.00%> (ø)
...rs/keptnwebhookcontroller/webhook_configuration.go	100.00% <0.00%> (ø)
klt-cert-manager/kubeutils/certificates.go	0.00% <0.00%> (ø)
klt-cert-manager/kubeutils/query.go	100.00% <0.00%> (ø)
...ptnworkloadinstance/reconcile_prepostevaluation.go	90.90% <0.00%> (+9.09%)	⬆️

Flag	Coverage Δ
component-tests	42.42% <ø> (+0.90%)	⬆️
keptn-lifecycle-operator	54.67% <ø> (ø)
klt-cert-manager	67.50% <ø> (?)
scheduler	21.17% <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
No Duplication information

[thschue]

lgtm