MDEV-9038 Binlog encryption tests

- created binlog_encryption test suite and added it to the default list
- moved some tests from rpl, binlog and multisource suites to extra
  so that they could be re-used in different suites
- made minor changes in include files

mysql-test/suite/binlog_encryption/rpl_gtid_basic.cnf

@@ -0,0 +1,24 @@
+!include my.cnf
+
+[mysqld.1]
+log-slave-updates
+
+[mysqld.2]
+init-rpl-role=       slave
+master-retry-count=  10
+skip-slave-start
+
+[mysqld.3]
+log-slave-updates
+innodb
+
+[mysqld.4]
+log-slave-updates
+innodb
+
+[ENV]
+SERVER_MYPORT_3=     @mysqld.3.port
+SERVER_MYSOCK_3=     @mysqld.3.socket
+
+SERVER_MYPORT_4=     @mysqld.4.port
+SERVER_MYSOCK_4=     @mysqld.4.socket