Compilation units currently contain pointers into allocated space that
contains the code of the respective function. This requires us to keep
the StreamingDecoder alive as long as compilation is still running
(including tiering).
This CL refactors this by having an additional redirection
(WireBytesStorage) which can point to either the StreamingDecoder or
the NativeModule. We only keep the code section buffer alive as long as
the StreamingWireBytesStorage is still in use.

I will further refactor memory ownership in a follow-up CL to not make
the AsyncCompileJob keep the StreamingDecoder alive.

R=ahaas@chromium.org

Bug: v8:8343,v8:7921,v8:8050
Change-Id: I780582c3217abf64000454f2c9c108b9ac9fbff1
Reviewed-on: https://chromium-review.googlesource.com/c/1319588Reviewed-by: Andreas Haas <ahaas@chromium.org>
Commit-Queue: Clemens Hammacher <clemensh@chromium.org>
Cr-Commit-Position: refs/heads/master@{#57317}