Create traces data type

[jalvz]

The spec defines 2 data types: metrics and logs (

package-spec/versions/1/data_stream/manifest.spec.yml

Lines 93 to 95 in e7102f8

	enum:
	- metrics
	- logs

).

For the upcoming APM integration we need a new traces data type.

[ruflin]

If we add a new data type, this should also be added to Elasticsearch @dakrone

[jalvz]

Thanks @ruflin, anything else I should be aware of?
Regarding EPR is just enough to add the new type to the enum above?

[ruflin]

For EPR, yes. It will also need to be added to Kibana to make sure the Kibana index pattern gets generated. @neptunian