Adds a new mlir-opt test-only pass, -test-spirv-cpu-runner-pipeline,
which runs the set of MLIR passes needed for the mlir-spirv-cpu-runner,
and removes them from the runner. The tests are changed to invoke
mlir-opt with this flag before running the runner. The eventual goal is
to move all host/device code generation steps out of the runner, like
with some of the other runners.
Recommit of 17e9752267. It was reverted
due to a build failure, but the build failure had in fact already been
fixed in e7302319b5.
9f6c632ecd