This CL allows for either of 'minimum' or 'initial' for MemoryDescriptor
and TableDescriptor. It also adds a flag for the reflection features.

R=binji@chromium.org,adamk@chromium.org
Bug=v8:7742

Change-Id: Icfd4825f63e1eb784a39d10f740d55e81489eba7
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1485243
Commit-Queue: Aseem Garg <aseemgarg@chromium.org>
Reviewed-by: Adam Klein <adamk@chromium.org>
Reviewed-by: Ben Smith <binji@chromium.org>
Cr-Commit-Position: refs/heads/master@{#60256}