Add support for distribution_points endpoint to submit distribution metrics

[afarbos]

I would like to be able to create distribution metrics using the golang API, however the client today only support count, rate and gauge.

Adding support for https://api.datadoghq.com/api/v1/distribution_points to submit distribution metrics, example in the python client

[github-actions]

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[therve]

Fixed in #1518 , will be in the next release. Thanks!