Test/add tests for block prover

[stanlou]

Add unit test coverage for proveBlock(), proveTransaction(), and proveTransactions() functions, including all assertion validations.

Test Coverage Improvements for protocol package :

Before:

• Statements: 32.28%
• Branches: 33.04%
• Functions: 30.93%
• Lines: 32.04%

After:

• Statements: 56.6%
• Branches: 47.82%
• Functions: 54.97%
• Lines: 57.06%

Closes #345