implement verifier-core

[jchartrand]

• consolidate common verification code from LCW and VerifierPlus into a shared nom package

• add support for eddsa-rdfc-2022-cryptosuite

[alexfigtree]

PR closed: #7

[alexfigtree]

Need to discuss with Rob

[alexfigtree]

Mostly done; On hold - waiting for integration, needs security-document-loader update

[alexfigtree]

Waiting on security document loader, nearing completion

[alexfigtree]

Leaving open to wait and see how verifier-core integration affects beta libraries