add enabled functions

[brettmc]

spec 1.34 requires logger, tracer, and instrument to have an enabled function. It doesn't do anything helpful yet, but #1349 should resolve this.

Closes: #1324
Closes: #1325
Closes: #1326

[codecov]

Codecov Report

Attention: Patch coverage is 46.15385% with 14 lines in your changes missing coverage. Please review.

Project coverage is 74.56%. Comparing base (17ad56a) to head (eb41aea).

Additional details and impacted files

@@             Coverage Diff              @@
##               main    #1350      +/-   ##
============================================
- Coverage     74.61%   74.56%   -0.05%     
- Complexity     2504     2517      +13     
============================================
  Files           355      355              
  Lines          7180     7206      +26     
============================================
+ Hits           5357     5373      +16     
- Misses         1823     1833      +10     

Flag	Coverage Δ
8.1	74.25% <46.15%> (-0.06%)	⬇️
8.2	74.49% <46.15%> (-0.02%)	⬇️
8.3	74.50% <46.15%> (-0.02%)	⬇️
8.4	74.47% <46.15%> (-0.02%)	⬇️

Flags with carried forward coverage won't be shown. Click here to find out more.

Files	Coverage Δ
src/API/Logs/NoopLogger.php	100.00% <100.00%> (ø)
src/API/Trace/NoopTracer.php	100.00% <100.00%> (+100.00%)	⬆️
src/SDK/Logs/Logger.php	100.00% <100.00%> (ø)
...rc/SDK/Metrics/DefaultAggregationProviderTrait.php	100.00% <ø> (ø)
src/SDK/Metrics/ObservableInstrumentTrait.php	90.00% <100.00%> (+1.11%)	⬆️
src/SDK/Metrics/SynchronousInstrumentTrait.php	85.71% <100.00%> (+2.38%)	⬆️
src/SDK/Trace/Tracer.php	100.00% <100.00%> (ø)
src/API/Metrics/Noop/NoopCounter.php	0.00% <0.00%> (ø)
src/API/Metrics/Noop/NoopHistogram.php	0.00% <0.00%> (ø)
src/API/Metrics/Noop/NoopObservableCounter.php	0.00% <0.00%> (ø)
... and 4 more

... and 4 files with indirect coverage changes

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[Nevay]

https://opentelemetry.io/docs/specs/otel/metrics/sdk/#instrument-enabled

The instrument Enabled operation MUST return false if [...] All resolved views for the instrument are configured with the Drop Aggregation.

Can be implemented by adding a MetricWriterInterface::enabled(Instrument) method:

• in MetricRegistry return isset($this->instrumentToStreams[spl_object_id($instrument)]);
• in SynchronousInstrumentTrait and ObservableInstrumentTrait return $this->writer->enabled($this->instrument);