Creating a different page preview for disambiguation pages.
This patch:
- modifies the Preview model to accept a new 'type' property
- modifies the Restbase Gateway to pass the 'type' prop to the Preview model
- creates a new template to accept both generic/disambig previews
- modifies the renderer to render the new template
- generates icons for new template through resource loader
- adds new i18n strings
- modifies event-logging "preview seen" event to send new "disambiguation" previewType
- updates event logging schema version
- adds tests for Preview model and renderer for new preview type
- does way too much? yes, yes it does.
Bug: T168392
Change-Id: Idc936cc3eabbdd99a3d98f43c66b4cdbb7d24917
