Query cancellation/timeout support

[penberg]

If a query takes a long time, applications may want to cancel them either manually or via a timeout mechanism. We should be able to use the sqlite3_progress_handler() to implement this where SQLite periodically checks if it's OK to keep running. We would have to track the execution time of individual queries.

Depends on https://github.com/tursodatabase/libsql-js/issues/122 for infrastructure on query timing.