Add required asterisk and validation support to MudField

As ever, a suggestion that might improve an already great product but only if you feel it would be a benefit to the wider user base.

I tend to use MudField as a wrapper for other elements such as a radio button group or a group of a few elements relating to a single result (e.g. two fields for weight and height together in a 'BMI Calculator' MudField).

As such, two things I think would be useful

• The ability to add the superscript * to the label to indicate that the contents of the MudField (e.g. a Radio Button Group) are mandatory to keep the look and feel the same across the app.
• Having a "Validator" option for the MudField.

I currently address the second requirement by including a hidden MudTextField in the form and then setting the Error parameter on the visible MudField to

_formErrors.Contains(String_Value_Associated_With_Hidden_MudTextField_Error)

I'm guessing there's probably a better way to do this?