Add support for using RDS IAM with canal

[samongyr-sq]

Attempting to use canal with RDS IAM Auth tokens results in ERROR 1105

ERRO[0013] canal start sync binlog err: start sync replication at binlog (mysql-bin-changelog.000003, 267160) error ERROR 1105 (HY000): Failed to register slave; too long 'report-password'
ERRO[0013] canal has failed. error: start sync replication at binlog (mysql-bin-changelog.000003, 267160) error ERROR 1105 (HY000): Failed to register slave; too long 'report-password'
panic: canal has failed

Is the mysql_clear_password auth plugin not supported?

[samongyr-sq]

According to #757, it should already be supported. But it might not actually be because of this line

[samongyr-sq]

Judging by MySQL Bug #43439, it appears this is an old (but unexpected) limitation of CHANGE MASTER

The password used for a replication user account in a CHANGE MASTER TO statement is limited to 32 characters in length. Trying to use a password of more than 32 characters causes CHANGE MASTER TO to fail (see MySQL docs)