Remove sw::Context members from the processor classes and removed
many related functions. Also, the Renderer::draw() function now takes
a const sw::Context object in, so it is no longer legal to modify
sw::Context object within the Renderer::draw() function.

Bug b/132280877

Change-Id: I890b5ba7db2306c02a96ec3e10496aa35c51bbe2
Reviewed-on: https://swiftshader-review.googlesource.com/c/SwiftShader/+/30950Tested-by: Alexis Hétu <sugoi@google.com>
Reviewed-by: Chris Forbes <chrisforbes@google.com>