feat(rhdh chart): Add option to specify RHDH route's targetPort

[pmacik]

Description of the change

In the legacy backstage chart, there was a way to change the target port of the RHDH route on OpenShift. That was useful in case of the oauth2-proxy auth provider introduced as extra container.

In the new standalone rhdh chart, the target port is hard-coded to be http-backend

This PR introduces a chart value opehshift.route.targetPort (with a default value of http-backend) that allows changing route's the target port.

Which issue(s) does this PR fix or relate to

• JIRA_issue_link

How to test changes / Special notes to the reviewer

Checklist

• For each Chart updated, version bumped in the corresponding Chart.yaml according to Semantic Versioning.
• For each Chart updated, variables are documented in the values.yaml and added to the corresponding README.md. The pre-commit utility can be used to generate the necessary content. Run pre-commit run --all-files to run the hooks and then push any resulting changes. The pre-commit Workflow will enforce this and warn you if needed.
• JSON Schema template updated and re-generated the raw schema via the pre-commit hook.
• Tests pass using the Chart Testing tool and the ct lint command.
• If you updated the orchestrator-infra chart, make sure the versions of the Knative CRDs are aligned with the versions of the CRDs installed by the OpenShift Serverless operators declared in the values.yaml file. See Installing Knative Eventing and Knative Serving CRDs for more details.

[rm3l]

Looks good. Let's update the schema now to fix the CI failures. Thanks.

[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

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