(feat-req) DogstatsdExporter: Support global labels

[nappairam]

We are using http://github.com/dialtone/metrics-exporter-dogstatsd as our metrics exporter.
We were little worried cause it was not maintained for sometime.

I am happy to see metrics team has taken http://github.com/dialtone/metrics-exporter-dogstatsd into official repo.

The old version 0.8.0 supports adding global tags to the exporter, which will be added to all the metrics. This is quite useful to add tags with server ids, from different servers.

When I tried to update to the latest one, I found the current version 0.9.0 is missing this feature.

Would you consider adding the support for global tags ?

And Thank you very much for adapting the dogstatsd exporter to official repo.

[tobz]

👋🏻

Thanks for opening this issue. Apologies for the breaking change around global labels: I had wanted to simplify things as much as reasonably possible while redesigning the internals, but it seems like I went a little too far. 😅

I'm definitely willing to add support for configuring global labels, and I'll try to review your PR within a day or two.