fix: clone extra_fields for Item

[gadomski]

Related Issue(s):

• Closes Item.clone() doesn't clone extra_fields #1600

Description:

Also added a specific test for Catalog, though both Catalog and Collection were handling it properly.

PR Checklist:

• Pre-commit hooks pass (run pre-commit run --all-files)
• Tests pass (run pytest)
• This PR maintains or improves overall codebase code coverage.
• Changes are added to the CHANGELOG. See the docs for information about adding to the changelog.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 92.30%. Comparing base (82cf0fb) to head (56a7ef2).
⚠️ Report is 1 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #1601   +/-   ##
=======================================
  Coverage   92.30%   92.30%           
=======================================
  Files          55       55           
  Lines        8397     8397           
  Branches      971      971           
=======================================
  Hits         7751     7751           
  Misses        458      458           
  Partials      188      188           

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[jsignell]

Thanks Pete!