[BUGFIX release] Add some missing types to preview types

[wagenet]

• Adds some new type tests for preview types
• Removes some non-public API from the preview types
• Adds some missing APIs to preview types

[chriskrycho]

Two alternative approaches that work well for spots like this:

1. Use declare:

   Suggested change

   	// Good enough for testing
   	let factory = {} as TemplateFactory;
   	expectTypeOf(setComponentTemplate(factory, {})).toEqualTypeOf<object>();
   	declare let factory: TemplateFactory
   	expectTypeOf(setComponentTemplate(factory, {})).toEqualTypeOf<object>();

2. Test the parameters and return type explicitly instead:

   Suggested change

   	// Good enough for testing
   	let factory = {} as TemplateFactory;
   	expectTypeOf(setComponentTemplate(factory, {})).toEqualTypeOf<object>();
   	expectTypeOf(setComponentTemplate).parameters.toEqualTypeOf<[TemplateFactory, object]>();
   	expectTypeOf(setComponentTemplate).returns.toEqualTypeOf<object>();

Both of these avoid needing the cast, which is not a particularly big deal here but is nice in the "modeling what we want to see" sense.