Implement these 4 instructions for x64 Liftoff:
- i64x2.widen_low_i32x4_s
- i64x2.widen_high_i32x4_s
- i64x2.widen_low_i32x4_u
- i64x2.widen_high_i32x4_u

We move the codegen for the *high* instructions into macro-assembler to
allow sharing of the optimized code sequence between TurboFan and
Liftoff.

Bug: v8:10972
Change-Id: I900b24f96ee55784220656cb2664283b03c32110
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2621862
Commit-Queue: Zhi An Ng <zhin@chromium.org>
Reviewed-by: Clemens Backes <clemensb@chromium.org>
Reviewed-by: Bill Budge <bbudge@chromium.org>
Cr-Commit-Position: refs/heads/master@{#72055}