Create an Aggregation API

[inetand]

Goal

Define internal Aggregation and View APIs for configuring metric processing and resolving metric streams.

Scope

• Define aggregation types and their configuration.
• Define instrument selection by name, kind, unit, and instrumentation scope.
• Configure stream name, description, attributes, aggregation, and cardinality limit.
• Resolve matching Views independently into stream configurations consumed by MetricStorage.
• Preserve defaults from the instrument and MetricReader when View values are omitted.

Concrete exporters implementation is out of scope.

Specification

• Aggregation
• View
• Stream Configuration
• Measurement Processing