CMCL-1542: Add option to decollide/deocclude towards follow target instead of LookAt target

[glabute]

Purpose of this PR

Currently, state.ReferenceLookAt is used for resolving occlusions, but sometimes people want to resolve based on the follow target instead.

Description here: https://forum.unity.com/threads/cinemachine-collider-target-follow-instead-of-lookat.1525138/

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

[codecov-commenter]

Codecov Report

Attention: Patch coverage is 49.09091% with 28 lines in your changes are missing coverage. Please review.

Project coverage is 26.74%. Comparing base (a497bbe) to head (592ef3c).

Files	Patch %	Lines
...achine/Runtime/Behaviours/CinemachineDecollider.cs	0.00%	15 Missing ⚠️
...achine/Runtime/Behaviours/CinemachineDeoccluder.cs	65.78%	13 Missing ⚠️

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Additional details and impacted files

@@            Coverage Diff             @@
##             main     #945      +/-   ##
==========================================
- Coverage   26.78%   26.74%   -0.04%     
==========================================
  Files         247      247              
  Lines       27878    27894      +16     
==========================================
- Hits         7466     7460       -6     
- Misses      20412    20434      +22     

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[AntoineCharton]

Is it supposed to damp the target screen position?

(Only happens when use follow target is enabled)

[glabute]

Is it supposed to damp the target screen position?

No it's not. Looking into it

[AntoineCharton]

Almost there! Should the screen position target do that?

[glabute]

Doesn't look like it's related to deoccluder. Does it happen without the deoccluder? If so, it's a separate issue.