[Proof of Concept] Remove all exceptions from fluid-fluid kernel

[efaulhaber]

With these remaining two @inbounds, the resulting device code does not contain any exceptions.
However, the WCSPH benchmark is only 2% faster on an Nvidia H100, and these two @inbounds are not safe, so there is no reason to do this.
This PR is just a reference to evaluate the impact of the remaining exceptions and is not meant to be merged.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 88.21%. Comparing base (4f938d3) to head (1ce0022).
Report is 3 commits behind head on ef/inbounds2.

Additional details and impacted files

@@              Coverage Diff              @@
##           ef/inbounds2      #79   +/-   ##
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  Coverage         88.21%   88.21%           
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  Files                15       15           
  Lines               492      492           
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  Hits                434      434           
  Misses               58       58           

Flag	Coverage Δ
unit	88.21% <100.00%> (ø)

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