bugfix for "visiblity optimization"

[ptahmose]

Description

This is fixing a bug with the "non-visible-tile-optimization" introduced with #78.
A unit-test ensuring proper operation of this case was added.

Type of change

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• This change requires a documentation update

How Has This Been Tested?

locally and unit-test added

Checklist:

• I followed the Contributing Guidelines.
• I did a self-review.
• I commented my code, particularly in hard-to-understand areas.
• I updated the documentation.
• I updated the version of libCZI following Versioning of libCZI depending on the type of change
  • Bug fix -> PATCH
  • New feature -> MINOR
  • Breaking change -> MAJOR
• I have added tests that prove my fix is effective or that my feature works.
• New and existing unit tests pass locally with my changes.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Comparison is base (6497366) 65.11% compared to head (784cc8f) 65.11%.

Additional details and impacted files

@@           Coverage Diff           @@
##             main      #80   +/-   ##
=======================================
  Coverage   65.11%   65.11%           
=======================================
  Files          81       81           
  Lines       10470    10470           
=======================================
  Hits         6818     6818           
  Misses       3652     3652           

Flag	Coverage Δ
windows-latest	65.11% <100.00%> (ø)

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