Factor the duplicate code out of 2D/3D/Cube LOD calculation and add the
mipLodBias field from the sampler descriptor.

Bug: b/129523279
Test: dEQP-VK.pipeline.sampler.*
Change-Id: I7e25fad13fbe3307dddb2dcb853ed638344ee4aa
Reviewed-on: https://swiftshader-review.googlesource.com/c/SwiftShader/+/30429
Presubmit-Ready: Nicolas Capens <nicolascapens@google.com>
Kokoro-Presubmit: kokoro <noreply+kokoro@google.com>
Tested-by: Nicolas Capens <nicolascapens@google.com>
Reviewed-by: Chris Forbes <chrisforbes@google.com>