feat(metrics-sdk)!: Metrics cardinality limit

[xuan-cao-swi]

Description

This PR introduces cardinality limits for metric attributes, as defined in the metrics SDK specification.

Users can configure the cardinality limit in two ways:

1. Through a view:

OpenTelemetry.meter_provider.add_view(
  'test_histogram',
  aggregation: OpenTelemetry::SDK::Metrics::Aggregation::ExplicitBucketHistogram.new,
  aggregation_cardinality_limit: 1
)

2. Through an exporter:

exporter_with_limit = ConsoleMetricPullExporter.new(aggregation_cardinality_limit: 100)

If no limit is provided, the default value of 2000 is used (also negative value will turn to 0 for the limit).

The cardinality limit is enforced during the aggregation update process. When the number of unique attribute combinations exceeds the limit, the extra data points are grouped into a separate data point with the attribute:

{ 'otel.metric.overflow' => true }

This overflow data point is treated like any other data point.

Future work: There is currently duplicated logic across different aggregation implementations. A shared base aggregation class should be introduced to reduce repetition.

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