UI: ability to rerun the verification of a Stage's current Freight

[Hidde Beydals]

Proposed Feature

We should make it possible to rerun the verification of a Stage's current Freight from the UI, as is currently possible using the CLI:

$ kargo verify stage --project=my-project my-stage

Motivation

You may want to retry a terminated (#1771) verification at a later moment, or simply be assured that things are still working as expected at any given time.

Suggested Implementation

[Kent Rancourt]

@jessesuen checking on whether you wanted this in v0.5.1.