Now that lazy deserialization has been removed, we can roll back all
the mechanisms we introduced to support lazy single-builtin
deserialization.

This CL moves serialized builtin code objects (i.e.
off-heap-trampolines in most cases) back into the startup snapshot.
Support classes for builtin serialization and deserialization, as well
as the builtins snapshot itself are removed. Templatization on the
allocator class is removed as well.

Tbr: delphick@chromium.org
Bug: v8:6666, v8:7990
Change-Id: I2a910f8d3278b7e27b5f18ad408361ebd18871cc
Reviewed-on: https://chromium-review.googlesource.com/c/1304539Reviewed-by: Jakob Gruber <jgruber@chromium.org>
Reviewed-by: Michael Lippautz <mlippautz@chromium.org>
Reviewed-by: Yang Guo <yangguo@chromium.org>
Commit-Queue: Jakob Gruber <jgruber@chromium.org>
Cr-Commit-Position: refs/heads/master@{#57160}