WIP Rewrite sample stats to use apache arrow

[aseyboldt]

This adds a new optional dependency to arrow and if it is enabled, sample stats can be collected in arrow arrays. This makes it easier for other libraries to collect the sampler stats into a trace.

The old custom system that uses an enum to describe the different datatypes is removed, so this is a breaking change.

TODO: Add back in divergance meta information.

[codecov-commenter]

Codecov Report

Patch coverage: 74.61% and project coverage change: -0.87 ⚠️

Comparison is base (b5054ca) 88.70% compared to head (bf5a2b9) 87.84%.

Additional details and impacted files

@@            Coverage Diff             @@
##             main       #4      +/-   ##
==========================================
- Coverage   88.70%   87.84%   -0.87%     
==========================================
  Files           9        8       -1     
  Lines        1620     1752     +132     
==========================================
+ Hits         1437     1539     +102     
- Misses        183      213      +30     

Impacted Files	Coverage Δ
src/math.rs	99.06% <ø> (ø)
src/adapt_strategy.rs	87.23% <66.66%> (-6.38%)	⬇️
src/cpu_state.rs	79.80% <66.66%> (-0.78%)	⬇️
src/nuts.rs	82.17% <71.63%> (-2.20%)	⬇️
src/cpu_potential.rs	88.97% <76.92%> (+13.97%)	⬆️
src/cpu_sampler.rs	91.54% <100.00%> (+0.04%)	⬆️
src/mass_matrix.rs	97.61% <100.00%> (+1.19%)	⬆️
src/stepsize.rs	88.75% <100.00%> (ø)

... and 1 file with indirect coverage changes

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