- Simplify `SnapshotSource` interface
- Expose some useful functions as public and decoupled from `Host`
- Expose most of the test utils for e2e testing

…re modular/reusable.

- Use e2e_invoke for invoking host functions in recording mode
- Separate network config and adjustment config into separate structs for easier testing/caching etc.
- Clean up the storage logic to clearly distinguish between snapshots with and without archive access
- Added some documentation for public functions/structs
- Added some basic test coverage. I didn't try to verify the math for every number, but I did sanity-check them. The host function simulation accuracy is mostly covered on `e2e_invoke` side.

This feature has to be used for changes that are considered 'breaking' from the semver standpoint, but those that we still want to integrate to RPC/SDK/Core.

… into sim_refactor

… into sim_refactor