Add 'throw_exceptions' option to Sender

Python Version(s) Tested: 3.10

Operating System(s): Ubuntu

📝 Summary

Some of the offline mode tests were failing due to error.args[0] not working with ValidationErrors, changes this to str(error) instead

Also this gave misleading error messages in the tests- would prefer offline mode tests to throw errors encountered by sender (and more widely, users should also have this choice). So adds throw_exception option to Sender which will throw exceptions when encountered instead of suppressing and logging (which is default behaviour). Changed all tests to use this

🔍 Diagnosis

Failing gridmetrics test

✔️ Checklist

• Unit and integration tests passing.
• Pre-commit hooks passing.
• Quality checks passing.