Removing |CodeStubAssembler| from |v8_base| source list (see
https://chromium-review.googlesource.com/c/v8/v8/+/1346329) leads to
linkage problems with some build configurations because it was explicitly
and implicitly included in |v8_base| code.

This CL decouple this code and fixes problems.

Bug: v8:7777
Change-Id: I58de5c62914bc77645ed6cc9114409890bc13189
Reviewed-on: https://chromium-review.googlesource.com/c/1372067Reviewed-by: Jakob Kummerow <jkummerow@chromium.org>
Reviewed-by: Benedikt Meurer <bmeurer@chromium.org>
Reviewed-by: Jakob Gruber <jgruber@chromium.org>
Commit-Queue: Jakob Gruber <jgruber@chromium.org>
Cr-Commit-Position: refs/heads/master@{#58200}