Feature: Add custom HTML element for Item Traits Data Entry Field

[farling42]

See how to use string-tags for input along with choices so that an entry from a predefined (localized) list can be selected or a manual string can be entered.

PF2E traits work very well, having the traits on the same line as new entries - but it has an Apache License.

[farling42]

The tagify library could do this, but the resulting HTML field is no smaller than what we currently have (and can't be collapsed when editing is not being done).