libobs: Restore only canvases that have video info

[exeldro]

Description

Restore only canvases that have video info

Motivation and Context

When you have an extra canvas from a plugin that is disabled or removed and you change the resolution of the main canvas it will stop the graphics thread completely. The log lines look like this:

17:26:03.069: Invalid video parameters specified
17:26:03.069: Failed restoring video mix for canvas 'Aitum Vertical'

obs_canvas_reset_video_internal will fail because internal video info is not set
restore_canvases will return false
obs_init_video will not start the graphics thread

How Has This Been Tested?

On windows 11 by installing Aitum Vertical and disabling it after it created a canvas. Changing the size of the main resolution stops the graphics thread.

Types of changes

• Bug fix (non-breaking change which fixes an issue)

Checklist:

• My code has been run through clang-format.
• I have read the contributing document.
• My code is not on the master branch.
• The code has been tested.
• All commit messages are properly formatted and commits squashed where appropriate.
• I have included updates to all appropriate documentation.