vulkan renderer definitions and public headers

The virgl stack has a good number of public header files that are defined and consumed by different projects:

Kernel/VMM or vtest in the diagram is what I call transport mechanisms. They don't parse most of the traffic between Mesa and virglrenderer.

Examples of traffic that the transport mechanisms don't parse are

• resource parameters (virgl_formats, VIRGL_BIND_* in virgl_hw.h)
• virgl capsets (virgl_capsets and virgl_caps_v* in virgl_hw.h)
• virgl protocol (VIRGL_CCMD_* in virgl_protocol.h)

Examples of traffic that the transport mechanisms do parse are

• blob resource types
• blob resource flags

These are new and are parsed because the transport mechanisms need to allocate differently and set up mappings for example.

For vulkan renderer, I need to add some new definitions

• context types (virgl or venus)
• venus capset
• venus protocol

The least intrusive change is to

• add context types to virgl_hw.h because they are things the transport mechanisms don't parse
• add venus capset to virgl_hw.h where virgl capsets are defined
• add venus protocol to a new protocol header

But we could also use the chance to clean up virgl_hw.h such that Vulkan bits do not end up in virgl_hw.h. Thoughts?

@gurchetansingh