Allow negation/exclusion for searchable fields

[murphyke]

Right now you can negate/exclude values for low-cardinality/bar-charted fields, but you can't do the same for searchable/high-cardinality fields.

[naegelyd]

This issue is asking for search controls to support exclusion lists. Currently, a search control allows the user to specify a list of values that the field must be in. The opposite could also be true. The search control could support a list of values that the field CANNOT be in.

For example, let's say you wanted to query for all variants in varify EXCEPT those in a handful of cohorts. Currently, to do this, you would need to add all the cohorts to the list in the search control and then go through that list and find all the cohorts you want to exclude and manually remove them. This would be much easier if you could just select the cohorts you want to exclude without needing to add all the cohorts first.