Allow table_guid to be None when searching for and deleting list items

[Andy-Grigg]

Closes #409

Allow table_guid to be set to None when instantiating a RecordListItem object. Document the conditions under which it is permissible to set the guid to None and validate that it is not set to None when not permitted, i.e. when adding items to a list.

It's not possible to give table_guid a default value of None without re-ordering the arguments, because record_history_guid is not optional. I have therefore documented the type explicitly as str | None, to indicate that it can be provided as either a string or None, but must be provided as one of these values.

If a RecordListItem is empty and it is passed to the add_items_to_list method, raise a ValueError. It is unfortunate that we cannot raise the exception earlier, but we don't know what the RecordListItem will be used for when it is instantiated.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 99.61%. Comparing base (294be93) to head (79328e5).
Report is 3 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #417      +/-   ##
==========================================
+ Coverage   99.58%   99.61%   +0.02%     
==========================================
  Files           4        4              
  Lines         726      778      +52     
==========================================
+ Hits          723      775      +52     
  Misses          3        3              

Flag	Coverage Δ
integration-ubuntu-latest-24.1	48.97% <66.66%> (+1.72%)	⬆️
integration-ubuntu-latest-24.2	79.04% <83.33%> (+0.39%)	⬆️
integration-ubuntu-latest-25.1	79.04% <83.33%> (+0.39%)	⬆️
integration-ubuntu-latest-25.2	85.73% <83.33%> (-0.64%)	⬇️
unittests	94.47% <100.00%> (-1.26%)	⬇️

Flags with carried forward coverage won't be shown. Click here to find out more.

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

🚀 New features to boost your workflow:

• ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.