This removes the {base::ReversedAdapter} class and uses
{base::iterator_range} instead. The types are inferred from what
{std::rbegin} and {std::rend} return.

Since src/base/adapters.h would only contain this one method after
this refactoring, it was merged into src/base/iterator.h.
Some includes of src/base/adapters.h were unused and hence dropped.

R=mlippautz@chromium.org

Bug: v8:9396
Change-Id: I597172ec790193b73af196d1afcd64bbed0a597d
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1798432Reviewed-by: Michael Lippautz <mlippautz@chromium.org>
Reviewed-by: Michael Starzinger <mstarzinger@chromium.org>
Commit-Queue: Clemens Hammacher <clemensh@chromium.org>
Cr-Commit-Position: refs/heads/master@{#63703}