[Feature] clear option

[AlanCrevon]

Bug, feature request, or proposal:

Feature request

What is the expected behavior?

Add optionnal button to clear a field.

It should be a suffix button on the input (a cross at the end of the input, maybe ?).

What is the current behavior?

Once a date is set, it cannot be unset.

What is the use-case or motivation for changing an existing behavior?

A date input is not always "required" (does not invalidate form)

Is there anything else we should know?

Love this library :+1: