New objects:
- Sampler
- Transform feedback
- Vertex Array

Change-Id: I701ea5fea75b81196290c3bdb3230cd471cc537b
Reviewed-on: https://swiftshader-review.googlesource.com/2796Tested-by: Alexis Hétu <sugoi@google.com>
Reviewed-by: Nicolas Capens <capn@google.com>