Allow PTZ control via dragging

[Sarah-Connelli]

Just putting this out there as it would make the card PTZ control functionality less cumbersome and modern.

In this video of a commercial NVR (used to use this before they replaced the 'community' version with a trial version instead), they have some really nice methods of doing things, the ability of click and dragging to control PTZ is really nice:

https://youtu.be/cBeYOFfSEk0?t=179

Would be a real improvement if such a method of controlling PTZ could be achieved in this card?

PS. That timeline control where one can select a number of cameras, and then with one UI timeline to be able to scrub all of them back and forth was what attracted me to that nvr back when the company had the community version of the software. It was just super efficient and worked straight off an external USB 3.0 raid HDD super fast with virtually no delays. But this kind of functionality would be only for the main Frigate UI however I doubt they can do it easily and just as smoothly simply because of the way Frigate stores its recordings, I believe Obseron uses an internal custom recording format which allows it to do that kind of magic so efficiently.

[dermotduffy]

That would be nice! Will leave it open as a feature -- more thumbs up, more priority when it comes to implementation. Obviously PRs always welcome :-)