deeply consider adding the cleanup API

[lastmjs]

CONSIDER PUTTING THIS IN 1.0 or NEXT

Right now the ic0.call_on_cleanup functionality is exposed indirectly through the Rust CDK. It will apparently invoke destructors for us, and so we use this to clean up the global JS resolve and reject callbacks. But this functionality is not exposed to the end developer...what if they want this functionality?

I'm trying to see if the Rust CDK team is interested in adding the ability for the developer to pass in a cleanup callback of their own during call construction. This would make it a lot easier for us to add this functionality to Azle, if it is desired.

This will not be a breaking change in the future, we should be able to easily add it into the options object for call.