Support Date fields in RelayForm

Support date picker as a form input for RelayForm. Assume that the date field would be used in the backend as time stamp.

[Sample Relay Form Usage](https://github.com/BadrIT/bractal/blob/master/docs/assets/relay_form/sample.relayForm.js)

For sample of a RelayForm form input fields, check the file : 
src/modules/coreUI/components/forms/Template.js