Exponential Bucket Histogram - part 3

[reyang]

Following #3462.

Changes

• Introduced a lookup-table-based leading zero algorithm.
• Improved the perf while handling IEEE 754 subnormal.
• Implemented the scale reduction calculation (auto-merging is not covered by this PR).
• Extracted math related functions to OpenTelemetry.Internal.MathHelper.

[cijothomas]

Approving to unblock progress on Exp. Histogram. No user facing impact until this is integrated with the SDK.

[codecov]

Codecov Report

Merging #3473 (91d7404) into main (7de3f00) will decrease coverage by 0.08%.
The diff coverage is 80.88%.

❗ Current head 91d7404 differs from pull request most recent head bf5143e. Consider uploading reports for the commit bf5143e to get more accurate results

@@            Coverage Diff             @@
##             main    #3473      +/-   ##
==========================================
- Coverage   86.43%   86.35%   -0.09%     
==========================================
  Files         268      269       +1     
  Lines        9660     9712      +52     
==========================================
+ Hits         8350     8387      +37     
- Misses       1310     1325      +15     

Impacted Files	Coverage Δ
...penTelemetry/Metrics/ExponentialBucketHistogram.cs	57.89% <41.17%> (-15.44%)	⬇️
src/OpenTelemetry/Internal/MathHelper.cs	91.89% <91.89%> (ø)
....Prometheus/Implementation/PrometheusSerializer.cs	77.77% <100.00%> (ø)
src/OpenTelemetry/Metrics/CircularBufferBuckets.cs	100.00% <100.00%> (ø)
...emetry.Api/Internal/OpenTelemetryApiEventSource.cs	76.47% <0.00%> (-5.89%)	⬇️
src/OpenTelemetry/Logs/OpenTelemetryLogger.cs	86.66% <0.00%> (-4.45%)	⬇️