[Form] Form show/hide capability

It is common requirement to be able to show/hide a form field on the basis of values of other fields (e.g. showing a textbox to input email id if send email checkbox is selected). This feature is present in WCM form foundation components (/libs/foundation/components/form). However, it is missing from core components version (/apps/core/wcm/components/form).
It would be a really nice feature for core form components, as there could be more customers looking to upgrade from old form foundation components (non Touch-UI based).

Start by comparing the existing behavior in /libs/foundation/components/form with the core form components at /apps/core/wcm/components/form. Define the conditional show/hide behavior for fields based on other field values, and verify that the core components provide the requested capability for customers upgrading from the foundation components.

Written by the indexing model from the issue text.