Add support for sampling days to screen / DISCount

[tnmygrwl]

darkecology#26

DISCount: https://arxiv.org/abs/2306.03151

[sarahakbar16]

As a user I want to be able to enter DISCount mode for a batch, label the given scans, and export the data.

Definition of Done:

Replace date w/ what you're supposed to label next

• Switch/Button -> Enter DISCount mode
• Add input date range capability
• Export data with confirmation
• Exit DISCount mode
• Test code changes
• Review