feat(providers): implement WitnessStateProvider

[Rjected]

This will be useful for implementing a block execution endpoint that works with outputs from debug_executionWitness

This should contain a witness and implement the required Reader traits like AccountReader

[nhtyy]

Hey Id be happy to give this a shot soon if youd like @Rjected

From my understanding this would be a type that implements StateProvider and is probably generic over another StateProvider, a witness is applied and this new type can store maps that covers all the accounts touched in the witness, any other account can then be delegated to the inner StateProvider.

In the ExecutionWitness, we should be able to pull out the addresses changed and store the new account info via the state field

And with the keys we can recover any updated storage slots