Filter SNVs by substitution, insertion, deletion

[atc3]

Maybe put under the "Group by SNV" radio button?

[atc3]

More details for this:

• For now, just have a group of checkboxes for "substitution", "insertion", and "deletion"
• Make this a new component and put it under the GroupBySelect component
• Only show the component in we're in "SNV" mode
• Make new observable attributes for this in configStore, and pass it along to the server as part of the query requests
• In the server, inside query.py, add SQL expressions to filter by the passed SNV filters. To filter for insertions, check that the ref field is blank (-). For deletions, check that the alt field is blank (-). For substitutions, neither can be blank.