dattcore: Create non-blocking to/from methods for objects with crypto, and asynchronous methods where non-blocking not possible

[ryanxcharles]

Sometimes we want to convert a buffer into a crypto object, such as a public key or an extended public key, or our own objects like ContentAuth, but we don't want the to/from methods to block. Unfortunately some of the crypto in the to/from methods do block, such as converting a compressed public key into a pubkey object. We need to create non-blocking methods for these objects.

• Anything that involves compressed public keys should have an alternative that uses uncompressed public keys, because converting to/from uncompressed does not do elliptic curve math and thus does not block.
• BIP32 extended public keys and private keys have the same issue, plus they also have a checksum in string format.

[ryanxcharles]

Fixed in a series of commits that integrate the new fullnode worker interface, particularly from 8b4dd5c to 617e7e7