[riscv64] Introduce dedicated JSBoundFunction to represent bound functions.

Port 97def807

Change-Id: If4f135be03e7ab719e091f02bdace49f9bcafcfa
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2928143


Commit-Queue: Brice Dobry <brice.dobry@futurewei.com>
Reviewed-by: Brice Dobry <brice.dobry@futurewei.com>
Cr-Commit-Position: refs/heads/master@{#74938}