Node's Buffer type is a UInt8Array under the hood but to provide better cross platform javascript support we can move to using the more generic ArrayBuffer. this shouldn't result in a breaking change since Buffer is a subclass of UInt8Array which is a subclass of ArrayBuffer, so we're just going up the inheritance chain. Acceptance criteria should include tests to ensure this assumption is correct.

In order to use ArrayBuffer only we would need to in house a lot of functionality and potentially have breaking changes in our BSON Binary class.
So we decided instead to keep Buffer as a bundled dependency and consolidate the types of our binary storage.