Make sure that out of slice point display is restricted to the z dimension

[AnniekStok]

Make another Points subclass that overwrites the out-of-slice display logic and restrict it to the last non-displayed dim. Use it for orthoviews and TrackPoints

Partial fix for #238

[codecov-commenter]

Codecov Report

❌ Patch coverage is 71.21212% with 19 lines in your changes missing coverage. Please review.
✅ Project coverage is 86.10%. Comparing base (815ab22) to head (7b6242e).

Files with missing lines	Patch %	Lines
...ker/data_views/views/layers/out_of_slice_points.py	67.79%	19 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #342      +/-   ##
==========================================
- Coverage   86.35%   86.10%   -0.25%     
==========================================
  Files          51       52       +1     
  Lines        4244     4305      +61     
==========================================
+ Hits         3665     3707      +42     
- Misses        579      598      +19     

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[cmalinmayor]

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