NC | Online Upgrade CLI

[romayalon]

Explain the changes

1. CLI -

   1. Added upgrade TYPE to noobaa-cli.
   2. Added upgrade - start, status, history actions.
   3. Created upgrade CLI errors, responses, help and validations.

2. ConfigFS - Added get_system_config_file() function used by status and history actions.

3. Tests - Added upgrade cli unit tests.

Issues: Fixed #xxx / Gap #xxx

1. Gap - currently start throws not implemented error - its logic will be added in the PR that implements the upgrade process.
2. Gap - Documentation will be added after all the PRs are done.
3. Gap/Idea - Currently on status/history we return the status/history of the config directory upgrade - we can also add --hostname/--all flag for providing the status/history of the RPM upgrade record of a specific host/all hosts.

Testing Instructions:

• [ ] Doc added/updated
• [x] Tests added