Add support for unicode tags in dogstatsd generation

[scottopell]

From https://docs.datadoghq.com/getting_started/tagging/#define-tags

Tags can be up to 200 characters long and support Unicode letters (which includes most character sets, including languages such as Japanese).

[blt]

which includes most character sets

The question that would need answering is which character sets are allowed. Otherwise I think it's a pretty achievable lift.

[scottopell]

I think this is just imprecise wording in the documentation, from what I understand unicode is the character set.

From the Agent's perspective we support whatever golang does, which should be all of unicode, in either utf-8 or utf-16 encoding (again, what golang supports).

[scottopell]

never seen this in the wild, not worth keeping this open