[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

❌ Patch coverage is 88.00000% with 3 lines in your changes missing coverage. Please review.
✅ Project coverage is 88.21%. Comparing base (d0fe7f6) to head (1ce0022).
⚠️ Report is 67 commits behind head on main.

Files with missing lines	Patch %	Lines
src/neighborhood_search.jl	66.66%	2 Missing ⚠️
src/util.jl	85.71%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main      #79      +/-   ##
==========================================
+ Coverage   88.19%   88.21%   +0.01%     
==========================================
  Files          15       15              
  Lines         483      492       +9     
==========================================
+ Hits          426      434       +8     
- Misses         57       58       +1     

Flag	Coverage Δ
unit	88.21% <88.00%> (+0.01%)	⬆️

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