Create GH workflow to build all controller artifacts (OCI image and Helm chart)

[morri-son]

Description
To be able to automate the release of the OCM controllers, we require a Github workflow that creates and publishes all artifacts for the controllers, which is the OCI image and the Helm chart. This workflow should later be intergrated into the workflow that orchestrates the full release (#863).

The workflow should

• trigger build of controller
• create and publish OCI image on ghcr
• create attestation for OCI image
• create Helm chart pointing to OCI image and publish on ghcr
• create final attestation for Helm chart

Done Criteria

• Workflow exists and can be called by other workflows
• Code has been reviewed by other team members
• Analysis of existing tests (Unit and Integration)
• Unit Tests created for new code or existing Unit Tests updated
• Integration Test Suite updated (includes deletion of existing unnecessary Integration Test and/or creation of new ones if required)
• Enduser Documentation updated (if applicable)
• Internal technical Documentation created/updated (if applicable)
• Successful demonstration in Review

[Skarlso]

@morri-son Add more meat. 🍖

[Skarlso]

Talk about reducing the amount of rebuilds.