Add more unit and integration tests for State Fraud Proofs

[Manav-Aggarwal]

Some suggestions for tests to add to baseapp_test.go in cosmos-sdk-rollmint:

1. Block with bad txs: Txs that exceed gas limits, validateBasic fails, unregistered messages (see TestRunInvalidTransaction)
2. Block with invalid appHash at the end
3. Corrupted Fraud Proof: bad underlying store format, insufficient key-value pairs inside the underlying store
   needed to verify fraud
4. Bad block, fraud proof needed, fraud proof works, chain halts (happy case)