Tracking Issue: Using common types across all forks

## Problem

Some data structures never change across forks, however they are still duplicated due to WET.

## Observation

@petertdavies created an issue to have a common Account type [here](https://github.com/ethereum/execution-specs/issues/2154#issuecomment-3886483804) and @SamWilsn asked whether we can do this for other types like `Address`.

This is a tracking issue for Sam's question.

Start with the linked Account discussion in issue #2154, then inspect how types are duplicated across the repository's forks. No files or tests are named in this tracking issue; done would require identifying suitable common types and defining the scope for consolidating them.

Written by the indexing model from the issue text.