CMCL-1591: Add SplineDollyLookAtTargets component

[glabute]

Purpose of this PR

CMCL-1591

New feature! Specifies LookAt data points for positions along a spline, so that a dolly camera looks at those places when it reaches specific positions on the spline.

New scene view tool to edit those points (works like SplineRoll tool):

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

Comments to reviewers

The tool icon is a placeholder, @JulienDidierjean is taking care of providing new icons.
Possible improvements (to think about):

• Add option to specify a Transform to look at instead of a hardcoded point done!
• Prettier inspector (Data Points list is ugly - but this is provided by the spline team) done!
• Direct access to tool via button on inspector done!
• Interacting with tool auto-selects the appropriate list item in inspector
• Improvements to the easing algorithm: maybe use a spline to connect the lookAt targets?
• Consider removing the option to disable easing (i.e. it's always on full)

Known Issues

• For some reason, SaveDuringPlay does not capture modifications to the data points (same problem for SplineRoll data)
• Dragging the index of a data point in the inspector does not properlyu reorder the list - this is a spline framework issue

@sebastienduverne Please review the user manual changes and figure out where to put links to the page.

[codecov-commenter]

Codecov Report

Attention: Patch coverage is 1.83486% with 214 lines in your changes are missing coverage. Please review.

Project coverage is 26.66%. Comparing base (7c09510) to head (939d416).
Report is 2 commits behind head on main.

Files	Patch %	Lines
...itors/CinemachineSplineDollyLookAtTargetsEditor.cs	0.00%	157 Missing ⚠️
.../Components/CinemachineSplineDollyLookAtTargets.cs	9.75%	37 Missing ⚠️
...ity.cinemachine/Editor/Utility/InspectorUtility.cs	0.00%	15 Missing ⚠️
.../Editor/PropertyDrawers/InputAxisPropertyDrawer.cs	0.00%	2 Missing ⚠️
...yDrawers/FoldoutWithEnabledButtonPropertyDrawer.cs	0.00%	1 Missing ⚠️
...or/PropertyDrawers/Vector2AsRangePropertyDrawer.cs	0.00%	1 Missing ⚠️
...inemachine/Editor/Utility/CinemachineSceneTools.cs	0.00%	1 Missing ⚠️

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Additional details and impacted files

@@            Coverage Diff             @@
##             main     #998      +/-   ##
==========================================
- Coverage   26.83%   26.66%   -0.17%     
==========================================
  Files         249      251       +2     
  Lines       28000    28207     +207     
==========================================
+ Hits         7513     7522       +9     
- Misses      20487    20685     +198     

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[glabute]

Replaced by #999