Show required fields to user on `ScoreSetCreator` and `ExperimentCreator` components

[davereinhart]

The ScoreSetCreator and ExperimentCreator components have a feature that disables the "Next" button on each stepper panel until all of the required fields have been filled out. Currently, there's no indication to the user which fields need to be filled out to proceed to the next step.

It would probably suffice to just add "(required)" to the label for each of those fields, but may be more maintainable to handle it programmatically using the stepFields lists that are already defined. One approach could be to keep the "Next" button enabled at all times and then display the relevant validation errors if the user clicks it without the required fields and/or use a red outline around each field that is required.