Pass the cluster count to the QuadRasterizer instead of using a rather nasty back dependency to the renderer.

This allows the cluster count to be adjusted per-draw without requiring synchronization around the count.

The primary goal of this change is that we can scale the number of clusters based on the complexity of the draw.

Bug: b/139142453
Change-Id: I0379e16568de402f186ee2dd1e8b2346bed30efd
Reviewed-on: https://swiftshader-review.googlesource.com/c/SwiftShader/+/35571Tested-by: Ben Clayton <bclayton@google.com>
Kokoro-Presubmit: kokoro <noreply+kokoro@google.com>
Reviewed-by: Chris Forbes <chrisforbes@google.com>
Reviewed-by: Nicolas Capens <nicolascapens@google.com>