[Feature Request] allow disabled dates in datepicker

Problem Statement

It is a pretty common use case for bots to use Input.Date for appointment booking. We would want users to pick one from all the available dates. Currently adaptive card Input.Date only supports min and max dates. It would be very nice if it also supports restricted dates like fluent UI https://react.fluentui.dev/?path=/docs/compat-components-calendar--default so we can disable unavailable dates.

Proposed solution

I see that the original Input.Date uses html datepicker which doesn't have a restricted dates options but AC can support fluent UI and fluent UI datepicker supports restricted dates. I propose to add restricted dates in the schema and add it as a parameter for Input.Date component.

Alternatives or Workarounds

I tried to write custom element like this https://learn.microsoft.com/en-us/adaptive-cards/sdk/rendering-cards/javascript/extensibility but the problem is that if I add a restrictedDates field to my inpute.Date element in the json I send from the bot, this field will be dropped because it is not in the schema

Start with the Adaptive Cards schema definition for Input.Date and the platform renderers that consume it. Review how min and max dates are passed to the datepicker, then determine how a restrictedDates property can be preserved by schema validation and applied consistently. Done means the property is accepted and unavailable dates cannot be selected.