Changes:
- Remove endianness transformations from WasmValue contstructors.
  WasmValue will now use the system's endianness. Remove
  CopyToWithSystemEndianness.
- Remove endianness transformation from global variable load/stores in:
  wasm-compiler.cc, liftoff-compiler.cc, wasm-objects{.cc, -inl.h}, and
  wasm-interpreter.cc
- Adjust SIMD tests that directly access part of a value by changing
  which lane they access within that value. We do that by introducing
  a LANE macro and use it over ReadLittleEndianValue.

Change-Id: I99e97c6eae72e9a135b184633ec266049803bb03
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2944437
Commit-Queue: Manos Koukoutos <manoskouk@chromium.org>
Reviewed-by: Zhi An Ng <zhin@chromium.org>
Reviewed-by: Clemens Backes <clemensb@chromium.org>
Reviewed-by: Michael Lippautz <mlippautz@chromium.org>
Cr-Commit-Position: refs/heads/master@{#75085}