This shrinks the WasmCode a bit more (to the minimum which is currently
required) and at the same time makes space for more flags to be stored
in a bitfield.

R=ahaas@chromium.org

Bug: v8:10254
Change-Id: I98a24e917a00d74dd2306f18d45525e82b245826
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2135738Reviewed-by: Andreas Haas <ahaas@chromium.org>
Commit-Queue: Clemens Backes <clemensb@chromium.org>
Cr-Commit-Position: refs/heads/master@{#67015}