DYN-8469: Disallow empty groups with pins

[zeusongit]

Purpose

While deleting nodes from groups, if the only remaining items in the group are a node and a pin, when removing the node should remove the group as well.

Declarations

Check these if you believe they are true

• The codebase is in a better state after this PR
• Is documented according to the standards
• The level of testing this PR includes is appropriate
• User facing strings, if any, are extracted into *.resx files
• All tests pass using the self-service CI.
• Snapshot of UI changes, if any.
• Changes to the API follow Semantic Versioning and are documented in the API Changes document.
• This PR modifies some build requirements and the readme is updated
• This PR contains no files larger than 50 MB

Release Notes

While deleting nodes from groups, if the only remaining items in the group are a node and a pin, when removing the node should remove the group as well.

Reviewers

@DynamoDS/dynamo

[github-actions]

See the ticket for this pull request: https://jira.autodesk.com/browse/DYN-8469

[avidit]

@zeusongit Safe to ignore smoke test failure here. Looks like some issues with the build agent.