N-API: expose function to suggest GC extends external memory

[mhdawson]

• Version: ALL
• Platform: ALL
• Subsystem: ALL

Add an api to all the application to give the GC a 'hint' that external memory should be extended. This should be used to optimization and be a no-op on any vm that does not support such a request.

For V8 it would be a wrapper around:

v8::Isolate::AdjustAmountOfExternalAllocatedMemory()

And have a similar implementation to Nan::AdjustExternalMemory().

The N-API team will get to this based on priorities, but this is a good place for others to contribute as well. If you start working on this, assign the issue to yourself and add a comment that you are working on it.

[chris--young]

I'd like to work on this

[cjihrig]

@chris--young are you still working on this? It looks like you worked on a commit.

[chris--young]

@cjihrig yea sorry for the delay, been pretty busy the past couple weeks. I just opened a pr for this #14310