Servantify Team CSV endpoint

[pcapriotti]

Servantify Team CSV endpoint. Since it does not seem to be straightforward to convert a Sem action into a SourceIO value, this PR introduces a new Servant combinator called LowLevelStream that directly accepts a StreamingBody as the return type of the handler.

Tracked by https://wearezeta.atlassian.net/browse/SQSERVICES-1522.

Checklist

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