Ability to adjust issue "Filter by" dropdown options.

Currently the "Filter By" dropdown has only predefined set of filters that can't be modified. Projects have various requirements and would like the ability to filter based on other criteria that have been collected within the forms.

As an example, we have an "Area" drop down available on our forms which get added in all our issues. We want to be able to filter by "Area" in the Issues window in iTwin.