With the removal of mlir-vulkan-runner (as part of #73457) in
e7e3c45bc70904e24e2b3221ac8521e67eb84668, mlir-cpu-runner is now the
only runner for all CPU and GPU targets, and the "cpu" name has been
misleading for some time already. This commit renames it to mlir-runner.
The assert message was previously ignored. The lowered IR now calls `puts` it in case of a failed assertion.
Differential Revision: https://reviews.llvm.org/D138647