Add Locking API for quickly creating custom named locks.

There should be a way to enter a named critical section with coco SQL client. Something similar to this API or an easier way to do this:

let lock = await db.lock("database.customLockName", leaseTimeoutMS);
// do my critical section things
await lock.extend(leaseTimeoutMS); // taking longer time than expected, increase lock lease time
// do my critical section things
await lock.release();

• leaseTimeoutMS should be application controlled as it depends on program correctness requirements and can be infinite.
• If deadlock arises, it will be an application task to recover.
• DB resources will not be spent to maintain locks. The locking compute will be fully maintained at the client lib.

Start by reviewing the JavaScript MySQL client’s public API and existing resource-management entry points; the issue does not name specific files or tests. Clarify the design and acceptance criteria for named locks, configurable or infinite leases, extension, release, deadlock handling, and client-side lock maintenance before implementation.