Add Nearest Neighbor Searcher as Alternative for Inter-/Extrapolation

[RuneDominik]

This PR adds an NearestNeighborSearcher Inter-/Extrapolation class for convenience. The name was chosen to reflect that this does not do any Inter-/Extrapolation at all.

[codecov]

Codecov Report

Patch coverage: 100.00% and project coverage change: +0.41 🎉

Comparison is base (b3839f1) 93.53% compared to head (83ea9aa) 93.94%.

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #232      +/-   ##
==========================================
+ Coverage   93.53%   93.94%   +0.41%     
==========================================
  Files          52       54       +2     
  Lines        2429     2544     +115     
==========================================
+ Hits         2272     2390     +118     
+ Misses        157      154       -3     

Impacted Files	Coverage Δ
pyirf/interpolation/base_interpolators.py	96.29% <ø> (ø)
pyirf/interpolation/__init__.py	100.00% <100.00%> (ø)
pyirf/interpolation/component_estimators.py	100.00% <100.00%> (+1.66%)	⬆️
pyirf/interpolation/nearest_neighbor_searcher.py	100.00% <100.00%> (ø)
...irf/interpolation/tests/test_base_interpolators.py	100.00% <100.00%> (ø)
...ion/tests/test_component_estimator_base_classes.py	97.24% <100.00%> (+1.20%)	⬆️
...erpolation/tests/test_nearest_neighbor_searcher.py	100.00% <100.00%> (ø)

... and 2 files with indirect coverage changes

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