embedding: refactor public `ArrayBufferAllocator` API

Use a RAII approach by default, and make it possible for embedders
to use the `ArrayBufferAllocator` directly as a V8
`ArrayBuffer::Allocator`, e.g. when passing to `Isolate::CreateParams`
manually.

PR-URL: https://github.com/nodejs/node/pull/26525


Reviewed-By: Gireesh Punathil <gpunathi@in.ibm.com>
Reviewed-By: Joyee Cheung <joyeec9h3@gmail.com>