The autoselect functionality was meant to enable user feedback for when
data was selected, but something else actually used, for example in case
the value "Auto" was chosen, or an incompatible one.
However, it has a few problems:
1. It was not really used, the only places in OBS were the legacy Video
Capture Device on macOS and the Video Capture Device on Windows.
2. It was never even fully implemented in the UI. In fact, the
properties view *only* supports it for obs_property_list, despite the
API theoretically allowing any data/property type.
3. The core obs_data seems like the wrong place for this kind of
interaction between plugins and UI. obs_data should carry data from one
place to another, some built-in feedback mechanism for the other
direction doesn't make too much sense. If the functionality is desired,
I think this should be rearchitectured as some place of explicit data
transfer.
Let's mark it as deprecated for future removal.
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