Add basic example showing how to use various metric instruments

[cijothomas]

Towards #1060

Changes

Adds a example which showcases the usage of various instruments. The stdout exporter is used to display metrics.
There'll be a separate PR which shows common customizations, like changing temporality, using views, changing interval etc.

Merge requirement checklist

• CONTRIBUTING guidelines followed
• Unit tests added/updated (if applicable)
• Appropriate CHANGELOG.md files updated for non-trivial, user-facing changes
• Changes in public API reviewed (if applicable)

[codecov]

Codecov Report

Patch coverage has no change and project coverage change: -0.1 ⚠️

Comparison is base (ecf0dda) 54.9% compared to head (4269069) 54.9%.

Additional details and impacted files

@@           Coverage Diff           @@
##            main   #1062     +/-   ##
=======================================
- Coverage   54.9%   54.9%   -0.1%     
=======================================
  Files        151     151             
  Lines      18242   18245      +3     
=======================================
  Hits       10025   10025             
- Misses      8217    8220      +3     

Impacted Files	Coverage Δ
...try-api/src/metrics/instruments/up_down_counter.rs	26.6% <0.0%> (-1.2%)	⬇️

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[TommyCpp]

Looks reaonable to me. I understand we have too many examples at this point but with the new metrics example I think this one will be really benificial for users. We can probably clean up some other examples to reduce maintaince burdan

[cijothomas]

Looks reaonable to me. I understand we have too many examples at this point but with the new metrics example I think this one will be really benificial for users. We can probably clean up some other examples to reduce maintaince burdan

Agree. I'll be able to help with some cleanups/consolidation of the examples.

[cijothomas]

@TommyCpp Could you merge please?

[gautamg795]

Does your example of recording data to a histogram here use the ExponentialBucketHistogram type under the hood, or is it using an explicitly bucketed histogram with some default value for the buckets?

[cijothomas]

Does your example of recording data to a histogram here use the ExponentialBucketHistogram type under the hood, or is it using an explicitly bucketed histogram with some default value for the buckets?

It follows the spec, which states that the default is ExplicitBucket aggregation, using the default buckets.
https://github.com/open-telemetry/opentelemetry-rust/blob/main/opentelemetry-sdk/src/metrics/reader.rs#L154