add ability to filter by item notes

[jagoly]

Summary

SUMMARY: Interface "Add 'n:' prefix for item filtering, to search through an items note."

Purpose of change

This is nice if we want to label a bunch of stuff for custom loot zones, but don't want to actually change the names of the items. It also means we can use whatever text we want, eg "n:kitchen" won't find kitchen units. Also possibly of use is just using n: or -n: alone, to filter items that do/don't have notes at all.

Describe alternatives you've considered

Just using labels like "kitchen_ chef knife", but that's a pain, and rather ugly.

Testing

Additional context

This could perhaps also work nicely with some method of mass-noting items. I might try to do that in another PR.