[DNM] Add dummy task, pipeline, and ITS for EC-2011 POC

[simonbaird]

For review bots: You can ignore this PR, it exists to test some pipelines and artifacts in Konflux. It won't be merged in this repo.

Summary

• Adds a dummy-check Tekton task that produces configurable pass/fail/warn results with a test-result attestation step (via the attest-test-result step action)
• Adds a reqd-task-poc-ec2011 pipeline that parses a Snapshot and runs the dummy-check task
• Adds hack/create-dummy-its.sh to create the IntegrationTestScenario in the cluster

Context

POC for EC-2011 — dog-fooding a required task in an ITS instead of the build pipeline.

Test plan

• ITS created in rhtap-contract-tenant namespace
• Pipeline triggers on PR and runs successfully
• Test-result attestation is created and attached to the image
• Conforma can discover and evaluate the attestation

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