Rename files according to nhs_*.jl

[LasNikas]

Keeping in mind that more searches will be added, then this could increase readability in the directory, no?

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 74.86%. Comparing base (940941a) to head (e5ae37d).

Additional details and impacted files

@@           Coverage Diff           @@
##             main      #16   +/-   ##
=======================================
  Coverage   74.86%   74.86%           
=======================================
  Files           7        7           
  Lines         191      191           
=======================================
  Hits          143      143           
  Misses         48       48           

Flag	Coverage Δ
unit	74.86% <ø> (ø)

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[efaulhaber]

I have a local branch depending on #8 and #9 where I move these files to a separate folder neighborhood_searches, so that we have neighborhood_searches/trivial.jl, neighborhood_searches/grid.jl and so on.