Add --push-secret option to oc new-build for when using --to-docker --to with registry requiring auth.

[GrahamDumpleton]

The oc new-build option allows you to specify --to-docker and --to to have resulting build pushed to a remote image registry, but it doesn't seem to be possible to specify a push secret at the same time, which means it isn't possible in one step to do this for a remote image registry which requires authentication.

Since pushing to a remote registry such as DockerHub would always require specifying a pushSecret, would make sense to make it easier by accepting a --push-secret option to oc new-build.

An alternative is to allow an annotation to be added to the secret so that it is automatically matched against a build configuration when a push secret is required. That is, similar to how one can specify an annotation on a secret with private Git repository credentials so they are automatically used. Am not aware of any annotation which currently does that.