Prevent errors when creating already existing tag through model entries.

[rtibbles]

Summary

Description of the change(s) you made

• Adds ignore_conflicts=True when bulk creating Tag through objects to prevent errors from duplicated entries which break copying, but are not an issue.
• Adds a TODO for future cleanup of Tag creation to leverage the same

Manual verification steps performed

I couldn't reproduce this so went for the minimal fix - as long as the Python tests pass, I think this is adequately covered by automated tests.

References

Fixes #4221

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[bjester]

Followed up on Slack about missing tags despite the error, but this looks good nevertheless

[bjester]

Thank goodness for ignore_conflicts!

[rtibbles]

Have done a bit more investigation here, and I now think I know why this has happened and can write a regression test for it, so will push another commit with that.