This CL generalized the previous check that a FunctionTemplateInfo
instance is not changed after being instantiated to a check for
immutability after being published. A FTI is considered published once
it is instantiated (set in a SharedFunctionInfo) or set as an accessor
on a JSObject. The published state is tracked in the flags field.
TurboFan relies on this immutabilty for concurrent access.

The immutability requirement was already met before this CL, but this
change enforces this by adding necessary checks.

Change-Id: I4d214e7aed8e04339072c2870caef1c28c772ed5
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2718147Reviewed-by: Ulan Degenbaev <ulan@chromium.org>
Reviewed-by: Toon Verwaest <verwaest@chromium.org>
Commit-Queue: Nico Hartmann <nicohartmann@chromium.org>
Cr-Commit-Position: refs/heads/master@{#73221}