Add custom models

[samfreund]

This allows for uploading of custom object detection models via the GUI.

Note #1685 ought to be merged prior to this one, as it contains the same edits.

[samfreund]

Someone should test that the files upload properly on a PI, I haven't tested it on that platform as I don't have one readily available.

[mcm001]

Do you think this would make sense as its own card on the settings page instead of piled in with all the other buttons?

[samfreund]

Do you think this would make sense as its own card on the settings page instead of piled in with all the other buttons?

I think that would also work. My reasoning was that these were files that would go on the device, so I put it in there. I can make it a separate card tho, that's not much work.

[samfreund]

fixes #1354

[samfreund]

@mcm001 this should be good to go

[gerth2]

Quick test on pi3, looks like the upload card is visible and "works" in the context it accepts files.

The front-end camera interface uses this logic to disallow selecting object detection when there's no backend for it available, is it possible to use the same mechanism on the settings page to hide the upload card on platforms where it can't be run?

[samfreund]

This check failed because of dependencies it looks like. Do we think it could be related to #1690?

[spacey-sooty]

This check failed because of dependencies it looks like. Do we think it could be related to #1690?

Nah CI is just a bit silly sometimes

[gerth2]

wheeeeee