Add statsd tag separator capability

[danielhochman]

What changed?
Add additional tagging support via configuration to the statsd reporter. Currently, stats are emitted with tags embedded directly in the name. For example, if the stat is hello.world and the tags are {universe: milkyWay, planet: earth} the stat will be emitted as:

hello.world.planet.earth.universe.milkyWay

This remains the default behavior.

With this PR, if a tag separator is specified in the config the stat will be emitted with tags using that separator. For example, if the stat is hello.world and the tags are {universe: milkyWay, planet: earth} and the separator is ,, the stat will be emitted as

hello.world,universe=milkyWay,planet=earth

Why?
Some statsd ingestion pipelines (e.g. Datadog and InfluxDB) support this form of stats tagging.

How did you test it?
Unit tests.

Potential risks

• Stats will not emit properly leading to a lack of visibility.

Is hotfix candidate?
No

[danielhochman]

@jbreiding Can you review this soon? It's blocking our upgrade path currently.

[jbreiding]

@jbreiding Can you review this soon? It's blocking our upgrade path currently.

apologies for the delay in review, thank you for the contribution.

I have a couple of comments.

[jbreiding]

Thanks for the contribution