[WIP] Implement Aggregation Storage

[lalitb]

Fixes #1197

Changes

Initial implementation for Aggregation Storage. This will be improved over in future PRs.

This PR is dependent on #1184 to be merged. Will make it ready for review after that.

For significant contributions please make sure you have completed the following items:

• CHANGELOG.md updated for non-trivial changes
• Unit tests have been added
• Changes in public API reviewed

[codecov]

Codecov Report

Merging #1198 (7717183) into main (44795b6) will increase coverage by 0.06%.
The diff coverage is 75.87%.

@@            Coverage Diff             @@
##             main    #1198      +/-   ##
==========================================
+ Coverage   93.44%   93.50%   +0.06%     
==========================================
  Files         185      184       -1     
  Lines        6720     6714       -6     
==========================================
- Hits         6279     6277       -2     
+ Misses        441      437       -4     

Impacted Files	Coverage Δ
...pentelemetry/sdk/metrics/aggregation/aggregation.h	100.00% <ø> (ø)
...ry/sdk/metrics/aggregation/histogram_aggregation.h	75.00% <0.00%> (ø)
...ry/sdk/metrics/aggregation/lastvalue_aggregation.h	0.00% <0.00%> (ø)
...elemetry/sdk/metrics/aggregation/sum_aggregation.h	75.00% <0.00%> (ø)
...ntelemetry/sdk/metrics/view/attributes_processor.h	81.25% <ø> (ø)
sdk/include/opentelemetry/sdk/metrics/view/view.h	66.67% <0.00%> (+3.04%)	⬆️
sdk/test/metrics/view_registry_test.cc	100.00% <ø> (ø)
...k/src/metrics/aggregation/histogram_aggregation.cc	100.00% <100.00%> (ø)
...k/src/metrics/aggregation/lastvalue_aggregation.cc	100.00% <100.00%> (ø)
sdk/src/metrics/aggregation/sum_aggregation.cc	100.00% <100.00%> (ø)
... and 2 more

[lalitb]

changes done as part of #1265

[lalitb]

changes done as part of #1265