Using import() function for code splitting

[mikeal]

In order to reduce the impact not the default bundle size, each method should use the import() function to get the crypto library it needs. Since all the methods are already async this wouldn’t require an API change and would result in some very code splitting for the consumers.

[mikeal]

Just to be clear, until esm comes out from under a flag this would be very annoying to implement. Not sure what the timeline is for that, but I think it’s actually pretty aggressive.