Add inputType for telephone element

Problem/Motivation

The Transformer is already handling 'tel' element type as a string, but it's not setting the input type to 'tel'.

Steps to reproduce

Add a telephone element to a webform and see that there is no inputType set for the element under ui part of the schema.

Proposed resolution

Add the input type 'tel' for telephone elements.

"ui:options": {
  "inputType": "tel"
}