feat: add basic metrics view

[xuan-cao-swi]

Description

I'd like to contribute on metrics view. I think view will be helpful for customized aggregation over default aggregation on instrumenting metrics.

1. Changed the location of data_points to metric_stream, because I think aggregation should act as aggregator that provide transformative (on data_points) feature rather than storage feature.
2. Didn't implement the logic for conflicting metric identities. For current implementation, it will export all the metrics with different aggregation if the metric_stream has multiple views applied.
3. Need schema_url as part of instrumentation selection. feat: Add basic support for schema_url #1237

[github-actions]

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