In preparation to use the hash table in the scope_info, we
setup a hashtable from name to indices.

Bug: v8:12315
Change-Id: I77f1eb40191c2fb2d40127e1e84dbc41ca2e4b70
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3386804Reviewed-by: Dominik Inführ <dinfuehr@chromium.org>
Reviewed-by: Igor Sheludko <ishell@chromium.org>
Commit-Queue: Victor Gomes <victorgomes@chromium.org>
Cr-Commit-Position: refs/heads/main@{#78646}