Compare_entities diff uses id instead of name where needed

Summary

Addresses https://gitlab.indiscale.com/caosdb/customers/f-fit/management/-/issues/94 / https://gitlab.com/linkahead/linkahead-pylib/-/issues/119
When comparing two properties or parents where at least one of these properties/parents do not have a name, only an id, compare_entities now uses the id as a key for the diff.
Test-MR: caosdb-pyinttest!84 (merged)

Focus

• Is this compatible with the crawler?
• Would it be better to instead use the id as primary key and name as fallback?

Test Environment

Manual Testing

Check List for the Author

• All automated tests pass
• Reference related issues
• Up-to-date CHANGELOG.md (or not necessary)
• Up-to-date JSON schema (or not necessary)
• Appropriate user and developer documentation (or not necessary)
• Annotations in code (Gitlab comments)

Check List for the Reviewer

• I understand the intent of this MR
• All automated tests pass
• Up-to-date CHANGELOG.md (or not necessary)
• Appropriate user and developer documentation (or not necessary)
• The test environment setup works and the intended behavior is reproducible in the test environment
• In-code documentation and comments are up-to-date.
• Check: Are there specifications? Are they satisfied?