Add ability to mark query result rows as a false positive/need followup/true positive

[aeisenberg]

Some users need to iterate over all results in a large result set. Some results are false positives and others need further follow up. Finally others are true positives.

A user should be able to mark results as belonging to one of a set:

• false positive
• true positive
• needs followup

And the results view should be able to toggle showing any or all of these groups.

An open question is if we will be able to carry over these sets across query runs. Perhaps we can key each element in the set by its source location (if one exists) and use that to keep track of set membership across runs.