Service: Add new ServiceFramework framework for writing HLE services

The old "Interface" class had a few problems such as using free
functions (Which didn't allow you to write the service handler as if it
were a regular class.) which weren't very extensible. (Only received one
parameter with a pointer to the Interface object.)

The new ServiceFramework aims to solve these problems by working with
member functions and passing a generic context struct as parameter. This
struct can be extended in the future without having to update all
existing service implementations.