Gives our generated a files an extension that isn't used for any other
purpose (that we know of). This is handy for tooling to be able to
quickly know if a file is 'ours'. This comes up in places like
IVsSymbolicNavigationNotify (go to definition).
* Add support for generating attributes on Razor assembly
* Generate ProvideApplicationPartFactoryAttribute on Razor assembly
* Generate RelatedAssemblyAttribute on application assembly
Pranav K
Ryan Nowak