Add DynamicHMC compatibility

[sethaxen]

This PR adds utility classes/functions so that Pathfinder's estimated metric can be used to initialize DynamicHMC. See the integration test for an example.

[codecov]

Codecov Report

Merging #30 (52b778d) into main (50c2f21) will increase coverage by 0.15%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##             main      #30      +/-   ##
==========================================
+ Coverage   98.88%   99.03%   +0.15%     
==========================================
  Files           8       10       +2     
  Lines         269      311      +42     
==========================================
+ Hits          266      308      +42     
  Misses          3        3              

Impacted Files	Coverage Δ
src/Pathfinder.jl	100.00% <100.00%> (ø)
src/integration/dynamichmc.jl	100.00% <100.00%> (ø)
src/woodbury.jl	100.00% <100.00%> (ø)

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