Retire access logs in favor of unified binary step log

## Context Currently the emulator knows how to verify big emulator steps through two different ways. One by recording accesses into access logs (which is a structured JSON), this is used by machine-solidity-step. And another way by recording accessed pages into a binary log, this is used when proving with zkVMs. Turns out we can use a single binary log format compatible with both, greatly simplifying the emulator. This will require significant changes in machine-solidity-step.