Kr/relationship definitions pt2

[rocktavious]

Resolves #

Problem

There was no Get or List for relationship definition AND no tests for the entire CRUD functionality

Solution

Add Get and List and tests

Checklist

• I have run this code, and it appears to resolve the stated issue.
• This PR does not reduce total test coverage
• This PR has no user interface changes or has already received approval from product management to change the interface.
• Does this change require a Terraform schema change?
  • If so what is the ticket or PR #
• Make a changie entry that explains the customer facing outcome of this change

[jasonopslevel]

LGTM!

[jasonopslevel]

Still LGTM!