Refactor libs' BN and Point away from monkey patches

[kajoseph]

The monkey patches and prototype overrides in the libs' crypto/bn.js and crypto/point.js cause issues when trying to use the underlying libraries elsewhere in projects.

These need to be refactored to at least use ES2015+ class-based inheritance as opposed to prototype overrides. Ideally, we could get rid of the dependence on BN.js and elliptic's Point altogether.

[it-education-md]

Hi @kajoseph @nitsujlangston ,
Can this task have priority right now, and is it worth working on at this point? If so, I’m happy to take it on.

From my understanding, the immediate goal is to remove the monkey patching and move away from the current prototype override approach by using ES2015+ class-based inheritance, while treating the broader replace bn.js, elliptic Point entirely goal as a separate ideal follow-up. Is that the right scope for this issue?