feat: group create, get, list command

[SafarMirek]

This PR adds group command to service-registry part of cli tool. Group actions were added in service-registry API and this PR adds there features to the CLI.

Verification Steps

1. Use rhoas service-registry group list to see list of existing groups
2. Create new group using rhoas service-registry group create
3. Use rhoas service-registry group list to see if group created in 2 is there
4. Use rhoas service-registry group get to get metadata of the created group

Type of change

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• Documentation change
• Other (please specify)