And add load / store paths to deal with data layouts that are not interleaved by lane.

Bug: b/126330097

Change-Id: Id7730a606d623ffe74ae57668216f05159972f10
Reviewed-on: https://swiftshader-review.googlesource.com/c/SwiftShader/+/25710Reviewed-by: Nicolas Capens <nicolascapens@google.com>
Tested-by: Ben Clayton <bclayton@google.com>