[clarity] Create sbtc-db data

[setzeus]

Description

This marks the kickoff for the new sbtc-db contract which is comparable to the sbtc-mini sbtc-registry contract. The purpose of this contract is purely state management. However, the design has changed so much that it's very likely that most, if not all, data structures need to be refactored and/or re-named.

Therefore, the goal of this issue is to create all the constants, vars, & maps that the updated SIP design requires.

Acceptance Criteria

• All error constants defined
• All required vars defined
• All required maps defined