[metric spec review] ConsoleExporter should support delta and cumulative

[dyladan]

    I haven't looked deeper so I could be wrong, it seems the ConsoleExporter is only supporting CUMULATIVE? https://github.com/open-telemetry/opentelemetry-js/blob/d154066354863e8c682b4aa488d79c7e914bf91c/experimental/packages/opentelemetry-sdk-metrics/src/export/ConsoleMetricExporter.ts#L41

The specification requires both CUMULATIVE and DELTA to be supported https://github.com/open-telemetry/opentelemetry-specification/blob/main/specification/metrics/sdk_exporters/stdout.md#opentelemetry-metrics-exporter---standard-output.

InMemoryExporter seems to be covering both

opentelemetry-js/experimental/packages/opentelemetry-sdk-metrics/src/export/InMemoryMetricExporter.ts

Line 68 in d154066

selectAggregationTemporality(_instrumentType: InstrumentType): AggregationTemporality {

.

Originally posted by @reyang in open-telemetry/community#1204 (comment)

[pichlermarc]

Self-assigning as I already have a PR open for that 🙂

[dyladan]

Moving to after GA milestone as it isn't a breaking change and there is a blocking comment