Today, if someone creates a self managed cluster using the "hypershift" CLI, they have to specify the exact release image they want, and there's no way to use the CLI to set the update channel.

An improvement to usability would be for us to make smart defaults for both the release image and update channel when no user input is provided.

Example Use Cases

User want's latest OCP version defaulted at cluster creation time.

User creates a hosted cluster and does not want to set the release image or update channel. The user's expectation is that the system will automatically use the latest release-image supported by the mgmt cluster's hypershift-operator, and that the update channel will match the stable-x.y of that release. 

User wants to supply a release-image and have the channel defaulted for them

User creates a hosted cluster and explicitly sets the release-image but does not supply a channel. The user's expectation is that the system automatically uses the stable-x.y channel that matches the release image supplied.

User wants to only supply a channel, and have the release-image defaulted

User creates a hosted cluster, and explicitly sets the update channel field but leaves the relase-image empty. The user's expectation is that the system automatically detects the most recent release-image for the channel provided.