Update flags
Update flags

Update flags:
* Add flag for SHOW GLOBAL STATUS
* Add flag for SHOW GLOBAL VARIABLES
* Add flag for SHOW SLAVE STATUS
* Use consistent naming for enable/disable booleans

roman-vynar/mysqld_exporter,roman-vynar/mysqld_exporter,growbots/mysqld_exporter,prometheus/mysqld_exporter,prometheus/mysqld_exporter