Summary:
This diff implements explicitly unlock advisory locks with WriteRpc:
1. Unlock all locks held by a transaction: traverse transaction reverse index and delete each of them from intentsdb.
2. Unlock a specific lock (lock key and lock mode has to be specified) held by a transaction: traverse transaction reverse index and delete the first one that matches the specified lock key and lock mode.
Jira: DB-14380

Test Plan: advisory_lock-test

Reviewers: hsunder, bkolagani

Reviewed By: hsunder, bkolagani

Subscribers: ybase, yql

Differential Revision: https://phorge.dev.yugabyte.com/D40565