Add option to filter gnomAD variants to variants in ClinVar

[nawatts]

[nawatts]

Implement this with filters on table columns (clinical significance in this case).

[sjahl]

We got a renewed request for this feature, so just dropping it in the Plan/Discuss column for more discussion.

[anneodonnell]

The functionality that would be the most helpful is if there was a check box in the ClinVar section, likely near where it says "Only show ClinVar variants that are in gnomAD" that allowed one to match the table of gnomAD variants to what is selected for ClinVar variants. This is needed to understand the characteristics of ClinVar variants that are in the gnomAD dataset.