Allow views to select on instrument unit

[jack-berg]

Implements spec PR #3184.

[codecov]

Codecov Report

Base: 91.10% // Head: 91.10% // Increases project coverage by +0.00% 🎉

Coverage data is based on head (2de2df1) compared to base (dfaa681).
Patch coverage: 100.00% of modified lines in pull request are covered.

Additional details and impacted files

@@            Coverage Diff            @@
##               main    #5255   +/-   ##
=========================================
  Coverage     91.10%   91.10%           
- Complexity     4876     4881    +5     
=========================================
  Files           549      549           
  Lines         14420    14428    +8     
  Branches       1371     1374    +3     
=========================================
+ Hits          13137    13145    +8     
  Misses          890      890           
  Partials        393      393           

Impacted Files	Coverage Δ
.../opentelemetry/sdk/metrics/InstrumentSelector.java	94.11% <100.00%> (+0.78%)	⬆️
...lemetry/sdk/metrics/InstrumentSelectorBuilder.java	100.00% <100.00%> (ø)
...emetry/sdk/metrics/internal/view/ViewRegistry.java	97.67% <100.00%> (+0.08%)	⬆️

Help us with your feedback. Take ten seconds to tell us how you rate us. Have a feature suggestion? Share it here.

☔ View full report at Codecov.
📢 Do you have feedback about the report comment? Let us know in this issue.

[jkwatson]

Seems weird to me, but doesn't seem harmful, and if the spec says we should do it 🤷🏽

[jack-berg]

Seems weird to me, but doesn't seem harmful, and if the spec says we should do it 🤷🏽

The argument that convinced me is allowing you to choose appropriate explicit bucket boundaries based on whether units are milliseconds or seconds, grams or milligrams, etc.