Adds support for KEDA auth

[skonto]

Changes

• Adds support for both TriggerAuthentication and ClusterTriggerAuthentication for the default prometheus trigger.
• Tested on OCP , see the related md file and the docs here.
• In the future we can evaluate if we can add authentication in front of the Prometheus API using kube-rbac-rpoxy so we can add e2e tests or check further if there is an option to enable something similar via the helm charts (didnt see any).
• Adds unit tests for the scaledobject creation, improves the logic with validation and increases coverage.
• In the future I will explore more advanced configuration eg. scale down policies.

  Fixes #25

  Release Note

  Support Keda TriggerAuthentication and ClusterTriggerAuthentication.
  

[codecov[bot]]

Codecov Report

Attention: Patch coverage is 87.31343% with 17 lines in your changes missing coverage. Please review.

Project coverage is 84.10%. Comparing base (752e522) to head (22368a9). Report is 36 commits behind head on main.

Files with missing lines	Patch %	Lines
...onciler/autoscaling/hpa/resources/scaled_object.go	90.62%	6 Missing :warning:
pkg/reconciler/autoscaling/hpa/helpers/helpers.go	87.09%	2 Missing and 2 partials :warning:
pkg/reconciler/autoscaling/hpa/resources/keda.go	88.57%	2 Missing and 2 partials :warning:
pkg/reconciler/autoscaling/hpa/keda_hpa.go	33.33%	1 Missing and 1 partial :warning:
...conciler/autoscaling/hpa/config/autoscaler_keda.go	0.00%	0 Missing and 1 partial :warning:

Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #29 +/- ## =========================================== + Coverage 66.07% 84.10% +18.02% =========================================== Files 6 8 +2 Lines 227 346 +119 =========================================== + Hits 150 291 +141 + Misses 66 39 -27 - Partials 11 16 +5 ```

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[knative-prow[bot]]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: ReToCode, skonto

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