Recreate integration tests module

## Issue Summary
From design doc:
> There are tests found in `sc_consensus_grandpa` ([link](https://github.com/paritytech/polkadot-sdk/blob/feac7a521092c599d47df3e49084e6bff732c7db/substrate/client/consensus/grandpa/src/tests.rs#L19)) that create a mock network to test general functionality. There are both startup, shutdown tests, as well as testing finalization of blocks and persistence of voter state. I think it would be prudent to replicate the same tests minus the ones that utilize the `ObvserverWork`.

## Acceptance Criteria
- Assess feasibility and recreate test cases found in tests module

## Previous Research
### Issue summary

- Recreate broader integration type testing of the consensus grandpa client over all modules.

### Other information and links

- Based on: https://github.com/paritytech/polkadot-sdk/blob/master/substrate/client/consensus/grandpa/src/tests.rs

### Estimate
4 weeks