Make IServiceProvider<T> public?

[GioAbq]

If we could make IServiceProvider interface public, it would be easier to check if ServiceProvider can resolve particular service, or not, instead of catching exception.

[retroandchill]

It's not documented anywhere but if you add <DefineConstants>$(DefineConstants);JAB_ATTRIBUTES_PACKAGE</DefineConstants> to your csproj file it makes the interface public.