CMCL-1665: confiner 2D dynamic float-to-int scaling

[glabute]

Purpose of this PR

CMCL-1665: CinemachineConfiner2D stops working when bounding shape is very large

Conversion between float world coords and the fixed point that Clipper expects was suffering when bounding shapes approaceh 1000 units in size. This is because the hardcoded scaling factor was tuned for small bounding shapes and was too precise for large shapes.

The fix was to dynamically adapt the scaling factor, keeping it the same for small shapes, but decreasing it gradually as the shapes got bigger.

Testing status

• Added an automated test
• Passed all automated tests
• Manually tested

Documentation status

• Updated CHANGELOG
• Updated README (if applicable)
• Commented all public classes, properties, and methods
• Updated user documentation

Technical risk

low

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Codecov Report

Attention: Patch coverage is 86.20690% with 4 lines in your changes missing coverage. Please review.

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Report is 140 commits behind head on main.

Files with missing lines	Patch %	Lines
com.unity.cinemachine/Runtime/Core/ConfinerOven.cs	86.20%	4 Missing ⚠️

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Additional details and impacted files

@@           Coverage Diff           @@
##             main    #1053   +/-   ##
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  Coverage        ?   27.33%           
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  Files           ?      256           
  Lines           ?    28686           
  Branches        ?        0           
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  Hits            ?     7841           
  Misses          ?    20845           
  Partials        ?        0           

Files with missing lines	Coverage Δ
com.unity.cinemachine/Runtime/Core/ConfinerOven.cs	74.62% <86.20%> (ø)

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[alexzaranek]

Validated that the Confiner now handles larger bounding boxes correctly. Changes looks good.