Implement dump state

## Issue summary

- By default user run fork without persistance of changes.
- User can use `--dump-state` flag to dump current state including his changes to provided file.
- User then later can start anvil from his localdump file using `--load-state ` flag
- User can use `-s, --state-interval ` flag to dump state to the disk every N secodns.

## Other information and links

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No files or tests are named. Start by locating the CLI entry points that define the fork and state-related flags, then trace how the current state is represented. Done means supporting --dump-state, --load-state, and periodic -s/--state-interval persistence as described.

Written by the indexing model from the issue text.