Replaces VkDescriptorImageInfo with a more concrete
SampledImageDescriptor, which contains an sw::Texture that SamplerCore
uses.

The parameters can be looked up statically only because the
shaderSampledImageArrayDynamicIndexing feature is currently not
supported.

Bug b/129523279

Test: dEQP-VK.texture.filtering.2d.formats.r8g8b8a8_unorm.nearest
Change-Id: I619b5b48b2b4552d9bfc70b087df2c31eabb49ea
Reviewed-on: https://swiftshader-review.googlesource.com/c/SwiftShader/+/28434
Presubmit-Ready: Nicolas Capens <nicolascapens@google.com>
Kokoro-Presubmit: kokoro <noreply+kokoro@google.com>
Tested-by: Nicolas Capens <nicolascapens@google.com>
Reviewed-by: Alexis Hétu <sugoi@google.com>
Reviewed-by: Ben Clayton <bclayton@google.com>