[Inputs][DateInputs] Allow clearing value using "undefined"

[kdikov82]

Currently, the NumericTextBox and the DateInputs require setting "null" to clear the value, but it would be beneficial if the same can be achieved by setting "undefined".

In the following example, if the clear button is clicked initially, all but the NumericTextBox will reset the value within the input: https://stackblitz.com/edit/na6ywm?file=src%2Fmain.vue

However, if the value in the DatePicker is changed and then the clear button is clicked, the value will remain.