Built in widget Title with Link should have the download file icon

AFFECTS
All supported TPs: 6.0+

TODO
When drag and dropping a "Title with Link" widget:

=> Add the following optional fields to the widget configuration:

• Main File Download - Xpath
  => Leave field blank by default
  => contextual help:

  Specifiy a xpath (schemaprefix:property) here, if you want to add an icon allowing a user to download the document's main file. e.g.: use file:content for a File document type, or a custom document type extending the File document type.

• Main File Download - Schema
  => Leave field blank by default
  => contextual help:

  Specifiy the schema where the main file to be downloaded is stored, if you want to add an icon allowing a user to download the document's main file. e.g.: use file if you specified file:content in the Main File Download - Xpath field.

• Main File Download - Filename Property
  => Leave field blank by default
  => contextual help:

  Specifiy the property holding the main file's filename, if you want to add an icon allowing a user to download the document's main file. e.g.: put filename here if you used file:content in the Main File Download - Xpath field.

• When the widget is generated, this is what the result could look like if filled with the values mentioned in the contextual help:

  <property name="file_property_name">file:content</property>
  <property name="filename_property_name">filename</property>
  <property name="file_schema">file</property>