Long Term Solution for osimage subcommand

[XudongLiuHarold]

Describe the feature request

• We need to find a long-term solution for osimage populate subcommand.
• Because this subcommand needs to run before the management cluster gets created, now we put it under the management-cluster plugin temporarily, but this is not a proper way to have a osimage populate sub command under the management-cluster plugin, we need to find a long term solution for this.

Describe alternative(s) you've considered

Affected product area (please put an X in all that apply)

• ( ) APIs
• ( ) Addons
• (x) CLI
• ( ) Docs
• ( ) IAM
• ( ) Installation
• (x) Plugin
• ( ) Security
• ( ) Test and Release
• ( ) User Experience
• ( ) Developer Experience

Additional context

[codegold79]

Looks like a short-term solution was merged with #4041, but a long term solution is still needed. I'm keeping this issue open as not yet fixed.