Thresholding

**Please describe the problem that needs to be solved by this feature**
When raw probability mappings are saved (cyto-dl outputs) we need to give the user a way to apply thresholds

**How important is this feature to you? (Software team will re-prioritize all tickets based on current workload)**
High Priority

**Describe the solution you'd like**
A widget in the plugin to test and apply multiple different thresholds

**Additional context**
Add any other context or screenshots about the feature request here.