This change is needed to implement {struct,array}.get_{s,u}.

Some functionality in wasm-compiler was factored out to helper functions
LoadWithAlignment and StoreWithValueType.

Bug: v8:7748
Change-Id: I2a04d09d40532f2389cc82b4c9ee3d8e003c5101
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2231347Reviewed-by: Clemens Backes <clemensb@chromium.org>
Reviewed-by: Jakob Kummerow <jkummerow@chromium.org>
Commit-Queue: Manos Koukoutos <manoskouk@chromium.org>
Cr-Commit-Position: refs/heads/master@{#68215}