Training UI: warning message for CSV input

### Description
In "Start a new model" route, if user bypasses the Curation tab and goes for Training tab and attempts to click on the Image Directory (or "Training Image Data CSV" as V1 suggested change), a message can be displayed above the input box stating "Complete Curation first or follow our (CSV file guidance)[link here]. "

This to ensure even if they use their own CSV, the file should be correctly structured, as the current error feedback message stem from cyto-dl is not helpful to troubleshoot if the CSV is not accepted by cyto-dl.

### Size
S?

### Additional Note
V?