I'd like to propose adding support for the sqlite3_wal_hook in rusqlite, inspired by the existing commit_hook and rollback_hook etc. This would allow users to monitor Write-Ahead Logging (WAL) events via a safe Rust interface.

Proposed Changes:

1. Feature Flag:
   • Introduce a feature flag (e.g., "wal_hook" or added with the "hooks" feature ) to keep this functionality optional.
2. Safe Callback Interface:
   • Similar to commit_hook, provide a safe Rust closure interface for the WAL hook, ensuring it adheres to Rust's borrowing and ownership rules.
   • Avoid direct exposure of raw pointers, offering a safe abstraction instead.