Hide exemplars

[jack-berg]

Resolves #4272.

• Make exemplar package internal
• Add method to reflectively assign ExemplarFilter to SdkMeterProviderBuilder

[codecov]

Codecov Report

Merging #4276 (a0a594a) into main (2c695a3) will increase coverage by 0.01%.
The diff coverage is 63.63%.

@@ Coverage Diff @@ ## main #4276 +/- ## ============================================ + Coverage 89.85% 89.86% +0.01%  - Complexity 4826 4827 +1  ============================================ Files 567 567 Lines 15016 15024 +8 Branches 1422 1422 ============================================ + Hits 13493 13502 +9  + Misses 1058 1056 -2  - Partials 465 466 +1 

Impacted Files	Coverage Δ
...io/opentelemetry/sdk/metrics/SdkMeterProvider.java	92.30% <ø> (ø)
...telemetry/sdk/metrics/SdkMeterProviderBuilder.java	96.66% <ø> (ø)
.../metrics/internal/aggregator/AggregatorHandle.java	93.10% <ø> (ø)
...gregator/DoubleExponentialHistogramAggregator.java	100.00% <ø> (ø)
...internal/aggregator/DoubleHistogramAggregator.java	100.00% <ø> (ø)
...internal/aggregator/DoubleLastValueAggregator.java	100.00% <ø> (ø)
...trics/internal/aggregator/DoubleSumAggregator.java	100.00% <ø> (ø)
...dk/metrics/internal/aggregator/DropAggregator.java	36.36% <ø> (ø)
...s/internal/aggregator/LongLastValueAggregator.java	95.45% <ø> (ø)
...metrics/internal/aggregator/LongSumAggregator.java	100.00% <ø> (ø)
... and 21 more

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