Add unit tests for OperatorSDK cmd layer

[jberkhahn]

Feature Request

Per the discussion with @estroz and at the triage meeting on Monday, it would be nice if the cmd layer of OperatorSDK was thoroughly tested with golang unit tests. This is an umbrella issue to track progress on that work. It would be best to focus efforts on the commands that will be surviving the kubebuilder refactor, which I believe are the commands listed here.

[jberkhahn]

#3247 for cmd/bundle

[jberkhahn]

#3318 for cmd/alpha/scorecard

[jberkhahn]

#3296 for cmd/completion

[jberkhahn]

#3411 for cmd/olm