Claim_V2 support

[mauricefisher64]

Claim V2 is the main change for the C2PA spec. It requires an new Claim object that distinguishes between "created" and "gathered" assertion. The SDK will be updated in a backwards compatible want to support 1.4 and 2.0 assertions seamlessly. Both Claim V2 and Claim V2 are allowed to live together.

This story is to plumb through Claim V2 support

Subordinate stories:

• Custom serializer/deserialize that can read 1.4-2.x. Claims #557
• Change Claim Signature URI to be full path #558
• Remove VC support/generation when writing Claim V2 manifests #553
• [] Support for timestamp V2 #547