Refactor natron build deps packages to work with Qt5 & Qt6

[acolwell]

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• I've followed the contributing guidelines to the best of my understanding
• I've read and understood the contributing guidelines
• I've formatted my code according to Natron's code style
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PR Description

What type of PR is this? (Check one of the boxes below)

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Improvement (non-breaking change which does not add functionality nor fixes a bug but improves Natron in some way)
• Breaking change (fix or feature that would cause existing functionality to change)
• My change requires a change to the documentation
  • I have updated the documentation accordingly

What does this pull request do?

• Create natron-build-deps-common package to hold all common deps.
• Modified natron-build-deps-qt5 to use new natron-build-deps-common package.
• Added natron-build-deps-qt6 package for Qt6 builds.

Have you tested your changes (if applicable)? If so, how?

Yes. Build pacman repo action builds packages successfully and the Windows installer build action also builds Qt5 installers with these refactored packages successfully.

[YakoYakoYokuYoku]

Same as #1044. I cannot approve this based on what it was said there.

[acolwell]

Same as #1044. I cannot approve this based on what it was said there.

This is completely unnecessary and just stonewalling. Please stop.

Refactoring this is necessary so that the windows packages can be used by both branches. In this particular case it is a cross-cutting concern for both branches since the Qt5 code would need to use the Qt5 package and the Qt6 code would use the Qt6 one. Both of them depend on a common package. Not doing this means I'll have to manage different sets of packages for each branch. That is unnecessary work and will make maintaining CI for both branches more annoying.

Have approval from rodlie and devernay.

[acolwell]

Thanks for the review.