[Access] Find solution to avoid emulator updates for API changes

[peterargue]

Currently, whenever the AccessAPI or ExecutionDataAPI are updated, PRs are needed against flow-go and flow-emulator. Most of the time, the emulator changes are just updating versions and adding some stubs.

Explore options to avoid emulator updates for new API endpoints.

One possible solution is to add default implementations of the API interfaces that return "unimplemented" when called. The emulator could then embed those implementations into theirs, inheriting the default behavior. That may not completely solve the issue, but there may be other options.