ENH: Implement queries and entity retrieval

Summary

See https://gitlab.indiscale.com/caosdb/customers/lfpb/management/-/issues/386.

Focus

Point the reviewer to the core of the code change. Where should they start
reading? What should they focus on (e.g. security, performance,
maintainability, user-friendliness, compliance with the specs, finding more
corner cases, concrete questions)?

Test Environment

How to set up a test environment for manual testing?

Check List for the Author

Please, prepare your MR for a review. Be sure to write a summary and a focus and create gitlab comments for the reviewer. They should guide the reviewer through the changes, explain your changes and also point out open questions. For further good practices have a look at our review guidelines

• All automated tests pass
• Reference related Issues
• Up-to-date CHANGELOG.md
• Annotations in code (Gitlab comments)
  • Intent of new code
  • Problems with old code
  • Why this implementation?

Check List for the Reviewer

• I understand the intent of this MR
• All automated tests pass
• Up-to-date CHANGELOG.md
• 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 spezifications? Are they satisfied?

For further good practices have a look at our review guidelines.

src/Entity.jl

@@ -1595,7 +1595,7 @@ Return true if the given `entity` has errors, false otherwise.
 """
 function has_errors(entity::Ref{_Entity})
 
-    return get_errors(entity) > 0
+    return get_errors_size(entity) > 0
 
 end
 
@@ -1606,7 +1606,7 @@ Return true if the given `entity` has warnings, false otherwise.
 """
 function has_warnings(entity::Ref{_Entity})
 
-    return get_warnings(entity) > 0
+    return get_warnings_size(entity) > 0
 
 end