Add tests for video camera video recording and fix subsequent recording

[chrisfromwork]

This review contains a few items:

1. SpectatorView.Compositor.UnityPlugin no longer tries to interpolate between video and audio times. There is now an assumption that audio samples/video samples will be provided by the unity editor based on the same start time.

2. Audio sample time provided from the Unity editor is now based off of the captured frame index + frame sample lengths. This prevents needing to interpolate between the AudioSettings.dspTime and the CaptureFrameIndex time. Previous calculations for doing this in the native plugin did not work correctly and seemed unnecessary. Interpolations between AudioSettings.dspTime and CaptureFrameIndex time can be conducted in the Unity editor as needed.

3. We now have tests to ensure that textures get created for both the elgato and black magic design frame providers when starting the SpectatorViewCompositor scene.

4. We now have tests for recording and playing videos recorded with the SpectatorViewCompositor scene.

5. SpectatorView.Compositor & SpectatorView.Compositor.UnityPlugin now return video file names when starting recording so that tests can cleanup generated files.

Breaking Change Details:

Notes:

This change fixes video encoding issues that occur when recording videos with the Video Camera filming solution. It redefines the UnityCompositorInterface and is therefore a breaking change (requires recompiling associated dlls). This break allows the editor to know the name of the video file recorded, which allows for playmode test cleanup.

Migration Instructions:

To migrate to codebases using this change, users need to do the following:

1. x64 Release versions of SpectatorView.Compositor.dll and SpectatorView.Compositor.UnityPlugin.dll.
2. Close any instances of Unity
3. Run tools\Scripts\CopyPluginsToUnity.bat (this will update the dlls within SpectatorView.Native within your local SpectatorView.

[matthejo]

Remove this if there's no tests yet?

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Refers to: src/SpectatorView.Unity/Assets/SpectatorView.Tests/EditorIntrinsicsCalibrationTests.cs:19 in 7aa64a9. [](commit_id = 7aa64a9, deletion_comment = False)

[matthejo]

Remove this if there's no tests yet?

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Refers to: src/SpectatorView.Unity/Assets/SpectatorView.Tests/EditorExtrinsicsCalibrationTests.cs:19 in 7aa64a9. [](commit_id = 7aa64a9, deletion_comment = False)