CMCL-0000: fix upgrader and legacy streaming bugs found in the Enemies demo project.

[glabute]

Upgrader was crashing when trying to upgrade the Enemies demo project from 3.0.0-pre.4.

Project was still using legacy CinemachineVirtualCamera components, and all the cameras lost their lenses and stopped being animatable when upgrading to anything over CM 3.0.0-pre.4.

[codecov-commenter]

Codecov Report

Attention: 149 lines in your changes are missing coverage. Please review.

Comparison is base (e7ec0e4) 20.98% compared to head (b41d6b3) 21.12%.

Files	Patch %	Lines
...chine/Editor/Upgrader/CinemachineUpgradeManager.cs	0.00%	70 Missing ⚠️
...nemachine/Runtime/Deprecated/LegacyLensSettings.cs	0.00%	32 Missing ⚠️
....cinemachine/Editor/Upgrader/UpgradeObjectToCm3.cs	0.00%	11 Missing ⚠️
...ine/Runtime/Deprecated/CinemachineVirtualCamera.cs	0.00%	6 Missing ⚠️
...e/Runtime/Behaviours/CinemachineSequencerCamera.cs	0.00%	5 Missing ⚠️
...emachine/Runtime/Deprecated/CinemachineFreeLook.cs	0.00%	5 Missing ⚠️
...machine/Runtime/Behaviours/CinemachineClearShot.cs	20.00%	4 Missing ⚠️
...Runtime/Behaviours/CinemachineStateDrivenCamera.cs	20.00%	4 Missing ⚠️
...chine/Runtime/Core/CinemachineVirtualCameraBase.cs	63.63%	4 Missing ⚠️
.../Editor/Obsolete/CinemachineVirtualCameraEditor.cs	0.00%	3 Missing ⚠️
... and 3 more

❗ Your organization needs to install the Codecov GitHub app to enable full functionality.

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #911      +/-   ##
==========================================
+ Coverage   20.98%   21.12%   +0.13%     
==========================================
  Files         245      245              
  Lines       27527    27458      -69     
==========================================
+ Hits         5777     5800      +23     
+ Misses      21750    21658      -92     

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.