DDS support

[DafuSHI]

Hello,

I'm now able to get metrics for RDS (mysql, postgres, sql server), DCS (redis) & DDS (mongo).
Just an issue with the filter feature that doesn't take into account the DDS metrics. Indeed, even if I remove metrics from metric_filter_config.yml, all Mongo metrics are scrapped.

I've quickly checked extensions.go file in collector directory. I think buildSingleDimensionMetrics function is used for RDS and DCS parts but there is no DDS part.

Could you provide me how to fix it please ?

Thanks and regards.