Support replication from MySQL 8.0 to MariaDB

The goal is to ensure that one can use MariaDB as a slave of a MySQL 8.0 server.

There are a few issues when replication from MySQL 8.0 -> MariaDB:

• As MariaDB server does not support the MySQL default authentication
  caching_sha2_password, one has to add another replication user using the mysql_native_password protocol.
• One has to change JSON columns to be of type TEXT (as the MySQL JSON format
  is different from MariaDB).
• One has to change the character set / collation from utf8mb4_0900_... to one supported by
  MariaDB, like utf8mb4 or utf8mb4_uca1400_ai_ci (starting from MariaDB 10.10).
  This is to be fixed in 11.4

MySQL 8.0 has added the following new events in the MySQL binary log that needs to be taken care of:

PARTIAL_UPDATE_ROWS_EVENT
TRANSACTION_PAYLOAD_EVENT
HEARTBEAT_LOG_EVENT_V2