Utilities for creating test chains and test transactions

[Rjected]

Describe the feature

We should have a utility that creates a ChainSpec and test chain, that can be used in consensus tests. It should also be possible to create different types of valid transactions using funded signers. This would allow for better integration testing of the consensus engine, for example we could replicate many of the test cases in hive as integration tests.

There should also be utilities for generating the state root on top of a block in tests.

Additional context

No response

[Rjected]

Closing this since the scope, and requirements for this to be complete, are unclear. If we want to test specific engine / consensus scenarios, or need to build a specific test tool, those can be more well defined in their own issues.