Allow setting custom data on QVideoFrame (From QImage, QByteArray, and multiplanar data)

What is the benefit? Why is this valuable?
This is related to the programmatic I\/O for media capturing.

What are common use cases?

• a user creates custom frames and records them to a video
• a user creates custom frames and sends them to video output.

Technical information
Add a constructor to QVideoFrame to set user-specific data.

API/Implementation details:
In the first stage, we're likely to agree on methods QVideoFrame::fromData and QVideoFrame::fromImage.
API review: https://codereview.qt-project.org/c/qt/qtmultimedia/+/536156

TODO:

• Implement both (it's supposed to be simple, just use QImageVideoBuffer, and QMemoryVideoBuffer).
• Add unit tests for both to tst_QVideoFrame.
• Cleanup the documentation of the functions.