Allow specifying a path to your own GT.M or MySQL backup when setting up replication

[Jon Tai]

Currently, ovreplicate and ovmysqlrepl both create their own backup on the primary when setting up the secondary. This is done automatically by the scripts over SSH. The backups are then transferred over the network.

In some cases, the backups could be quite large, and the bandwidth between the primary and the secondary may not be very fast. Of course, the network must be fast enough to stream updates, but it could still take a long time to transfer many gigabytes of backups to initially configure the secondary. If a recent backup file already exists on the secondary, it would save lots of time to be able to point ovreplicate/ovmysqlrepl at the existing backup.

[Jon Tai (jontai)]

The GT.M backup can be specified with the -f argument to ovinstancerepl, but we currently cannot specify a path to a MySQL backup.