Feature: #81656 - Select view helper supports required argument
See forge#81656
Description
The select view helper supports the optional argument 
        required according to this:
https://www.w3schools.com/tags/att_select_required.asp
Impact
Set the "required" argument like this:
<f:form.select property="category" required="1" options="{categories}" />        
        Copied!
    
The rendered html output is this:
<select required="required" name="tx_ext[model][category]">
    <option value="...">...</option>
</select>        
        Copied!