This changes the ordered hash data structures in ordered-hash-table.h to
use InternalIndex as the type used for indices, rather than int.

This makes the interface more similar to the (unordered) hash tables in
dictionary.h and hash-table.h

Bug: v8:7569

Change-Id: I2389b0c7d103eb7c33c5ed620b16eb198109b54c
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2503949
Commit-Queue: Frank Emrich <emrich@google.com>
Reviewed-by: Igor Sheludko <ishell@chromium.org>
Reviewed-by: Marja Hölttä <marja@chromium.org>
Cr-Commit-Position: refs/heads/master@{#70873}