caopengllayer: move opengl startup to dedicated function

The code will be moved towards a real OpenGL provider module in the future. This commit starts writing the module like so by ensuring there is a valid OpenGL startup function for the module.

Currently, the usage of the vout_display prevents from allocating the views and everything from within the OpenOpenGL function, but they'll get moved in later patches which will include setting up dedicated callbacks for the rendering.

changed milestone to %4.0

added Component::Video: macOS / iOS / tvOS / visionOS label

added MRStatus::Reviewable label

approved this merge request

added MRStatus::Acceptable label and removed MRStatus::Reviewable label

added MRStatus::Accepted label and removed MRStatus::Acceptable label

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added 36 commits

• fa7509b7...bfd6ba9e - 32 commits from branch videolan:master
• c59ed71c - caopengllayer: move Open to avoid forward declarations
• 6873b7f8 - caopengllayer: move vout_display_operations
• 3eb8d1fb - caopengllayer: remove forward declarations
• 089d8cba - caopengllayer: move opengl startup to dedicated function

Compare with previous version

enabled an automatic merge when all merge checks for 089d8cba pass

merged