Store API: add projection hints #8606
Description
Is your proposal related to a problem?
Projection hints was introduced to upstream Prometheus' Select interface recently. In order to support projection pushdown in Thanos Store, we need to expose projection hints through Thanos Store API first, mainly the Series API.
Describe the solution you'd like
Add new fields to Series API request to allow passing projection include (boolean) and projection labels (string slice).
As the first step, we can just expose the hints and no need to implement the actual projection pushdown. The actual pushdown can be implemented in Thanos Store Implementation which is more performant for such pattern like the Thanos Parquet Gateway.
Describe alternatives you've considered
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Additional context
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