* Add the cache type
* Add cache unit tests
* Test cache concurrency
* Add the instrumentCache
* Use the instrumentCache to deduplicate creation
* Drop unique check from addAggregator
* Fix aggregatorCache* docs
* Update cachedAggregator and aggregator method docs
* Remove unnecessary type constraint
* Remove unused errAlreadyRegistered
* Rename to not shadow imports
* Add changes to changelog
* Fix changelog English
* Store resolvers in the meter instead of caches
* Test all Aggregator[N] impls are comparable
* Fix lint
* Add documentation that Aggregators need to be comparable
* Update sdk/metric/internal/aggregator.go
Co-authored-by: Anthony Mirabella <a9@aneurysm9.com>
* Update sdk/metric/instrument.go
Co-authored-by: Anthony Mirabella <a9@aneurysm9.com>
* Update sdk/metric/instrument.go
Co-authored-by: Anthony Mirabella <a9@aneurysm9.com>
* Update sdk/metric/internal/aggregator_test.go
Co-authored-by: Anthony Mirabella <a9@aneurysm9.com>
* Fix pipeline_test.go use of newInstrumentCache
Co-authored-by: Anthony Mirabella <a9@aneurysm9.com>
