VxAdmin: Allow Deleting CVR Imports Individually

[adghayes]

Currently, CVR imports can only be removed in VxAdmin all at once. There's a "Clear All Tallies and Results" button, but no option to clear a single import.

In practice, this can lead to a frustrating problem where an incomplete or otherwise incorrect import is imported later in the results process and, in order to remove it, all CVR imports have to be removed and re-imported. I'm not very clear on what issues would lead to this situation, but we know customers have hit it before (IIRC, Warren) and requested this feature.

[adghayes]

This doesn't really fall into Continuous Export, but wanted to flag while @arsalansufi is still wrapping up CVR work.

@mattroe do you want to prioritize this for any particular milestone? IMO it's a very nice-to-have in the certified project and, unless things have changed significantly, it should be fairly low lift.

[arsalansufi]

@adghayes I went ahead and tagged this with the nh-march milestone for consideration for the upcoming NH deployments (as per this Slack comment)

[mattroe]

I think this is mostly applicable to county-deployments than town-deployments, but thanks for highlighting it for consideration. Initial take is it's more important for mvcp than nh-march