The two instructions are fused into a single Sadalp instruction,
improving performance of quantized neural network operator
implementations such as XNNPACK.

This change also includes some formatting changes to the unit
tests that were made automatically by clang-format, which I am
happy to revert if preferred.

Bug: v8:11546
Change-Id: I2afc8940a52186617cffd276c82733ad3020b728
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2878742
Commit-Queue: Daan de Graaf <daagra@google.com>
Reviewed-by: Zhi An Ng <zhin@chromium.org>
Cr-Commit-Position: refs/heads/master@{#74952}