BUG#49978: Replication tests don't clean up replication state at the end

Major replication test framework cleanup. This does the following:
 - Ensure that all tests clean up the replication state when they
   finish, by making check-testcase check the output of SHOW SLAVE STATUS.
   This implies:
    - Slave must not be running after test finished. This is good
      because it removes the risk for sporadic errors in subsequent
      tests when a test forgets to sync correctly.
    - Slave SQL and IO errors must be cleared when test ends. This is
      good because we will notice if a test gets an unexpected error in
      the slave threads near the end.
    - We no longer have to clean up before a test starts.
 - Ensure that all tests that wait for an error in one of the slave
   threads waits for a specific error. It is no longer possible to
   source wait_for_slave_[sql|io]_to_stop.inc when there is an error
   in one of the slave threads. This is good because:
    - If a test expects an error but there is a bug that causes
      another error to happen, or if it stops the slave thread without
      an error, then we will notice.
    - When developing tests, wait_for_*_to_[start|stop].inc will fail
      immediately if there is an error in the relevant slave thread.
      Before this patch, we had to wait for the timeout.
 - Remove duplicated and repeated code for setting up unusual replication
   topologies. Now, there is a single file that is capable of setting
   up arbitrary topologies (include/rpl_init.inc, but
   include/master-slave.inc is still available for the most common
   topology). Tests can now end with include/rpl_end.inc, which will clean
   up correctly no matter what topology is used. The topology can be
   changed with include/rpl_change_topology.inc.
 - Improved debug information when tests fail. This includes:
    - debug info is printed on all servers configured by include/rpl_init.inc
    - User can set $rpl_debug=1, which makes auxiliary replication files
      print relevant debug info.
 - Improved documentation for all auxiliary replication files. Now they
   describe purpose, usage, parameters, and side effects.
 - Many small code cleanups:
    - Made have_innodb.inc output a sensible error message.
    - Moved contents of rpl000017-slave.sh into rpl000017.test
    - Added mysqltest variables that expose the current state of
      disable_warnings/enable_warnings and friends.
    - Too many to list here: see per-file comments for details.

mysql-test/suite/rpl/r/rpl_row_conflicts.result

@@ -1,9 +1,5 @@
-stop slave;
-drop table if exists t1,t2,t3,t4,t5,t6,t7,t8,t9;
-reset master;
-reset slave;
-drop table if exists t1,t2,t3,t4,t5,t6,t7,t8,t9;
-start slave;
+include/master-slave.inc
+[connection master]
 call mtr.add_suppression("Slave: Can\'t find record in \'t1\' Error_code: .*");
 [on slave]
 SET @old_slave_exec_mode= @@global.slave_exec_mode;
@@ -24,6 +20,7 @@ a
 1
 [on slave]
 ---- Wait until slave stops with an error ----
+include/wait_for_slave_sql_error.inc [errno=1062]
 Last_SQL_Error = Could not execute Write_rows event on table test.t1; Duplicate entry '1' for key 'PRIMARY', Error_code: 1062; handler error HA_ERR_FOUND_DUPP_KEY; the event's master log master-bin.000001, end_log_pos 346 (expected "duplicate key" error)
 SELECT * FROM t1;
 a
@@ -31,6 +28,7 @@ a
 ---- Resolve the conflict on the slave and restart SQL thread ----
 DELETE FROM t1 WHERE a = 1;
 START SLAVE SQL_THREAD;
+include/wait_for_slave_sql_to_start.inc
 ---- Sync slave and verify that there is no error ----
 Last_SQL_Error = '' (expected no error)
 SELECT * FROM t1;
@@ -50,12 +48,15 @@ SELECT * FROM t1;
 a
 [on slave]
 ---- Wait until slave stops with an error ----
-Last_SQL_Error = Could not execute Delete_rows event on table test.t1; Can't find record in 't1', Error_code: 1032; handler error HA_ERR_KEY_NOT_FOUND; the event's master log master-bin.000001, end_log_pos 982 (expected "can't find record" error)
+include/wait_for_slave_sql_error.inc [errno=1032]
+Last_SQL_Error (expected "duplicate key" error)
+Could not execute Delete_rows event on table test.t1; Can't find record in 't1', Error_code: 1032; handler error HA_ERR_KEY_NOT_FOUND; the event's master log master-bin.000001, end_log_pos END_LOG_POS
 SELECT * FROM t1;
 a
 ---- Resolve the conflict on the slave and restart SQL thread ----
 INSERT INTO t1 VALUES (1);
 START SLAVE SQL_THREAD;
+include/wait_for_slave_sql_to_start.inc
 ---- Sync slave and verify that there is no error ----
 Last_SQL_Error =  (expected no error)
 SELECT * FROM t1;
@@ -64,6 +65,7 @@ a
 [on master]
 DROP TABLE t1;
 [on slave]
+include/rpl_reset.inc
 ######## Run with slave_exec_mode=IDEMPOTENT ########
 set @@global.slave_exec_mode= 'IDEMPOTENT';
 ==== Initialize ====
@@ -107,3 +109,4 @@ a
 DROP TABLE t1;
 [on slave]
 SET @@global.slave_exec_mode= @old_slave_exec_mode;
+include/rpl_end.inc