Description: 1. Added support for caching_sha2_password in
             libmysqlclient.
             2. Added new option
             MYSQL_OPT_GET_SERVER_PUBLIC_KEY in
             libmysqlclient.
             3. Added support to set
             MYSQL_OPT_GET_SERVER_PUBLIC_KEY in
             libmysqlclient based tools.

Reviewed-By: Bharathy Satish <bharathy.x.satish@oracle.com>
             Ramil Kalimullin <ramil.kalimullin@oracle.com>