chore: move StorageRootHash out of zk module

[giwaov]

Summary

• move StorageRootHash from the zk module to the state machine/root rollup interface exports
• update internal and downstream imports to use sov_rollup_interface::StorageRootHash

Closes #1652

Testing

• rustfmt +stable --check on changed Rust files, excluding crates/common/src/lib.rs because sparse checkout is missing sibling modules needed by rustfmt module resolution
• git diff --cached --check