sdkapi
* move Descriptor to sdkapi, add test * rename Descriptor to sdkapi * precommit * Move the rest of the sdkapi * use alias for Observation and Measurement * Changelog * pr num * comment Measurement and Observation * swap comments * move->moved
* Remove quantile definition * Complete removal of Quantile-related function * Comment in selector/simple/simple.go * Remove 'quantile' in mmsc * Rename array->exact * Update changelog * Add PR number * Rename exact benchmark * New test for exact timestamps * Add timestamp tests * More test * From feedback * Apply suggestions from code review Co-authored-by: Tyler Yahn <MrAlias@users.noreply.github.com> * Samples->Points * Rename Co-authored-by: Tyler Yahn <MrAlias@users.noreply.github.com>