Mitigate missing aspect ratio issue

[MGaetan89]

Pull request

Description

This PR uses the video size as a fallback when computing the video aspect ratio, when the tracks don't contain the video dimension.
This results in the aspect ratio quickly changing, while loading the first frames, but it still happen a lot less often compared to before #466.

Changes made

• Try to compute the aspect ratio from the video size, if the tracks don't provide the video dimension.
• Change the aspect ratio default value back to 1f.
• Change the methods computing an aspect ratio to return null is the value can not be computed.

Checklist

• Your branch has been rebased onto the main branch.
• APIs have been properly documented (if relevant).
• The documentation has been updated (if relevant).
• New unit tests have been written (if relevant).
• The demo has been updated (if relevant).
• All pull request status checks pass.

[github-actions]

Code Coverage

Overall Project	46.59% -0.29%	🟢
Files changed	1.85%	🟢

Module	Coverage
:pillarbox-player	47.18% -0.24%	🟢
:pillarbox-ui	0% -0.71%	🟢

Files

Module	File	Coverage
:pillarbox-player	VideoSize.kt	100%	🟢
	PlayerCallbackFlow.kt	78.03% -1.68%	🟢
:pillarbox-ui	PlayerSurface.kt	0% -4.68%	🟢