Introduce new SignatureScheme enum variant for Robust ECDSA and use it in the contract. #1638
Description
Background
The first step in integrating Robust ECDSA in the MPC code is to upgrade the SignatureScheme enum variant to support Robust ECDSA as a new domain and make the necessary contract changes to support creating a new domain for Robust ECDSA.
User Story
As a node operator I want to be able to support the new Robust ECDSA scheme.
Acceptance Criteria
The MPC contract supports creating a new domain for Robust ECDSA. The MPC nodes will initially ignore these domains.