Asynchronous instrument gaps and resets on delta temporality

[legendecas]

Spec: https://github.com/open-telemetry/opentelemetry-specification/blob/main/specification/metrics/supplementary-guidelines.md#asynchronous-example-attribute-removal-in-a-view

We need to detect gaps and resets and prevent producing negative outputs for observable counters aggregated by SumAggregator.

A basic implementation is to add monotonicity support to SumAggregator and perform a conditional diff on SumAggregate.diff.