Calculate delta sums for delta async counter/up-down-counter types

[MrAlias]

Fix #3278

Clarification of the expected async counter/up-down-counter behavior:

instrumentation will always record a cumulative value and if a user overrides the temporality to be delta the exported data needs to be converted to delta.

This updates the NewPrecomputedDeltaSum function to return an Aggregation implementation that conforms to this behavior.

[codecov]

Codecov Report

Merging #3398 (10b316c) into main (ccbc38e) will increase coverage by 0.0%.
The diff coverage is 92.1%.

Additional details and impacted files

@@          Coverage Diff          @@
##            main   #3398   +/-   ##
=====================================
  Coverage   77.9%   77.9%           
=====================================
  Files        164     164           
  Lines      11323   11359   +36     
=====================================
+ Hits        8822    8857   +35     
  Misses      2303    2303           
- Partials     198     199    +1     

Impacted Files	Coverage Δ
sdk/metric/internal/sum.go	97.5% <92.1%> (-2.5%)	⬇️
sdk/trace/batch_span_processor.go	81.1% <0.0%> (+0.8%)	⬆️

[jmacd]

Nice! 🎉