Allow user to specify custom prompts

Provide an interface in the data generator web GUI which allows them to adjust the prompts being used in the data generator backend. The suggested workflow is that right-clicking an action which causes prompting should give the option to adjust the prompt(s) for that action. Local browser storage should be used to remember a user's prompts, and some kind of visual marker should indicate that their prompt(s) for that action is/are modified.