Fast, reliable, and complete search index consistency check and fix

In JCR-3506, JCR-3516, and JCR-3517 improvements were made to the search index consistency checker that allows the execution of fast and reliable consistency checking and fixing in busy and live environments.

These improvements need to be incorporated into our patched JR 2.2 version. In addition, in order to leverage this new functionality, we need to override the way a consistency check is run during startup in our own repository code. This is because in Jackrabbit, the search index consistency check on startup runs before the cluster node is synchronised, and this means we cannot do a double check at that time. We need to postpone the check until after the cluster node is started.

We also may consider making the consistency check available from the console.