feat: View cleanups

[cijothomas]

Fixes #2985

Continuing from #2984 and #2982

This removes the new_view way of creating a View. Instead users are expected to pass anything implementing View trait. For convenience, View is implemented for Fn(&Instrument) -> Option<Stream>, so this can be used to add a view.

This allowed a lot of other cleanups. If there is a need, more additive changes can be done to make it easier to apply view for the common scenario.

Example of future additions (not part of this PR!):

meter_provider_builder().with_view_on_instrument(name: "Foo", steam: Stream::builder().name("foo-new"));
meter_provider_builder().with_view_on_instrument(name: "Foo*", steam: Stream::builder().unit("unit-new"));
meter_provider_builder().with_view_on_instrument(name: "*", steam: Stream::builder().aggregation(Aggregation::Drop));

[codecov]

Codecov Report

Attention: Patch coverage is 90.00000% with 9 lines in your changes missing coverage. Please review.

Project coverage is 81.4%. Comparing base (3cdc62e) to head (a33760c).
Report is 1 commits behind head on main.

Files with missing lines	Patch %	Lines
opentelemetry-sdk/src/metrics/instrument.rs	25.0%	6 Missing ⚠️
opentelemetry-sdk/src/metrics/mod.rs	96.2%	3 Missing ⚠️

Additional details and impacted files

@@          Coverage Diff          @@
##            main   #2988   +/-   ##
=====================================
  Coverage   81.3%   81.4%           
=====================================
  Files        126     126           
  Lines      24634   24570   -64     
=====================================
- Hits       20043   20000   -43     
+ Misses      4591    4570   -21     

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