Update to how session state is managed for EVM

[TheNewAutonomy]

As a developer I want all unit tests to pass so that we have a high degree of confidence that the functionality is working and repeatable.

Acceptance criteria

All unit tests pass, specifically all unit tests that involve snapshot, storage or session state.

Tasks

1. • Storage state and snapshot state is no longer public, instead there's WorldState. However, KVM interacts directly with storage and snapshot state so we need a solution to allow KVM to work, ideally without modifying Nethermind's EVM assembles. Ideally we are able to work without modifying those assemblies then we can merge in future EVM support changes without modifications. Really, we should abstract KVM specific functionality from the underlying EVM assemblies for this reason.
2. • Update unit tests relating to KVM state so we can ensure KVM continues to run reliably and we can test over time as we make future modifications to KVM.