Better constants handling

[atselikov]

What is the desired change?

Based on code review last week it would be nice to change the way we deal with constants:

from kaos_cli.constants import PACHYDERM, BACKEND
...
return self.state_service.get(PACHYDERM, 'workspace')

->

from kaos_cli import constants
...
return self.state_service.get(constants.PACHYDERM, 'workspace')

How will this change improve kaos?

More transparency in constants handling

Any thoughts on the implementation approach?

Code refactoring