Make DbTemplate inherit from DbItem and align their APIs
Add template items into fake items collection so that template items can be queried using Sitecore item APIs
Make sure BaseIDs from the DbTemplate propagate not only to Template.BaseIDs but also to the TemplateItem as a value of __Base template field
Make sure __Base template field can be worked with not only by ID but also by Name
Add __Base template field to every Template when FakeDataProvider creates it during GetTemplates()