This CL adds prefixed load scalar and floating point
instructions to the assembler and uses it during code generation
if the processor supports it. They have also been added to the disassembler and the simulator.

Drive-by: emit_prefix is now making sure a trampoline doesn't
get emitted in between prefix and suffix. Assembler needs to
block it using BlockTrampolinePoolScope.
Drive-by: more CHECKs are added to the assembler to make sure
immediate values have the correct length.

Change-Id: Ic5e38926c65364bc97aba0b7638dde5f365ec706
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3582479Reviewed-by: Junliang Yan <junyan@redhat.com>
Reviewed-by: Milad Farazmand <mfarazma@redhat.com>
Commit-Queue: Milad Farazmand <mfarazma@redhat.com>
Cr-Commit-Position: refs/heads/main@{#79970}