Memory mode: Adding support for synchronous instruments - explicit histogram

[asafm]

Epic

This is one of many PRs that implement #5105. See the complete plan here.
Specifically, this PR adds the implementation of MemoryMode for the synchronous instrument: explicit histogram.

What was done here?

This PR, relative to Exponential Histogram PR, is rather trivial. It contains:

• It changes DoubleExplicitBucketHistogramAggregator by adding a reusable MutableHistogramPointData and when REUSABLE_DATA is set, it simply re-uses that reusable point to store the aggregated result and returns it.
• Added a mutable version of HistogramPointData
  • Extracted 2 validation functions from ImmutableHistogramPointData into a shared class, to be used also at the mutable version.
• Added another test to the garbage collection benchmark test.
  • Worked nicely as it immediately failed and I quickly found out why (auto-boxing of Long in tight loop)

It is based on #6136; hence, once it is merged, I'll merge it from the main branch to show its true content.

I will convert it from draft to PR once the previous PR is merged.

[codecov]

Codecov Report

Attention: 19 lines in your changes are missing coverage. Please review.

Comparison is base (737dfef) 91.03% compared to head (ca98743) 90.94%.

Files	Patch %	Lines
...trics/internal/data/MutableHistogramPointData.java	80.89%	2 Missing and 15 partials ⚠️
...gator/DoubleExplicitBucketHistogramAggregator.java	81.81%	0 Missing and 2 partials ⚠️

Additional details and impacted files

@@             Coverage Diff              @@
##               main    #6153      +/-   ##
============================================
- Coverage     91.03%   90.94%   -0.10%     
- Complexity     5648     5670      +22     
============================================
  Files           618      620       +2     
  Lines         16438    16535      +97     
  Branches       1663     1682      +19     
============================================
+ Hits          14965    15037      +72     
- Misses         1011     1020       +9     
- Partials        462      478      +16     

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[jack-berg]

Just a couple of minor comments but looks good. Also, can you rebase and mark ready for review?

[asafm]

@jack-berg I fixed all comments and rebased it from the main branch.