Add cryptosuites ecdsa-rdfc-2019 and ecdsa-jcs-2019

[dlongley]

The current implementation is for P-256 and uses RDFC, but the standard changed its name to ecdsa-rdfc-2019, uses a new data integrity v2 context, and additionally allows P-384. We should allow backwards compatible usage of ecdsa-2019 but also add the new name and P-384 support. We should add JCS cryptosuite support as well or spin that off into its own library.

We could also deprecate this library and create an ecdsa-rdfc-2019 one that supports P-256 and P-384 and another ecdsa-jcs-2019 one -- and leave this library be. One way or another, we need to add the above capabilities.

[dlongley]

See: https://github.com/w3c/vc-di-ecdsa

[BigBlueHat]

@dlongley it looks like that "deprecation" is happening via replacement with this library: https://github.com/digitalbazaar/ecdsa-rdfc-2019-cryptosuite

Is JCS also being implemented somewhere?

Are you cool if I update this repo's readme to point to https://github.com/digitalbazaar/ecdsa-rdfc-2019-cryptosuite and possibly archive it?

[dlongley]

@BigBlueHat, yes, you can update it to point to ecdsa-rdfc-2019-cryptosuite but I'm not sure we have removed it from all active projects yet so we need to confirm that before archival.