Add Confirmation Messages for Actions or Errors When Data/Features Are Missing

[leomignot]

In certain areas, provide confirmation messages to indicate whether an action has been successfully processed or if there is an error or missing data. Examples:

• Export annotation test data button should give feedback when no test data is available ?
• Provide confirmation or warning messages when models lack features in the prediction and visualization sections of the annotation module ?

[emilienschultz]

Right. Done.