Add hand tracking toggle to OpenXR settings

[ada-tv]

Also actually implements the setting loading/saving functions so the settings will persist and there's a stub for saving tracker calibration offsets that'll be useful later once we support something that can keep track of the tracker roles

Fixes #2285

[JulianGro]

CodeChecker complains about unused parameter 'ownership'. Is that a false positive (or something we should ignore)?
That probably came from #2072 and the nightly CodeChecker update not having run yet.

Testing worked fine. We probably shouldn't be throwing an error when having hand tracking disabled and hand tracking being used though. On my Quest 1, it automatically switched to hand tracking when I put my controllers down.
Putting controllers down, picking them back up, putting them down again:

[09/02 16:26:32] [CRITICAL] [openxr.context] XR_ERROR_PATH_INVALID: Failed to get interaction profile path.
XR_ERROR_PATH_INVALID: xrPathToString(path == XR_NULL_PATH)
[Previous message was repeated 1 times]
[09/02 16:26:54] [INFO] [openxr.context] Controller 0: Interaction profile changed to '/interaction_profiles/oculus/touch_controller'
[09/02 16:26:54] [INFO] [openxr.context] Controller 1: Interaction profile changed to '/interaction_profiles/oculus/touch_controller'
XR_ERROR_PATH_INVALID: xrPathToString(path == XR_NULL_PATH)
[09/02 16:27:07] [CRITICAL] [openxr.context] XR_ERROR_PATH_INVALID: Failed to get interaction profile path.
XR_ERROR_PATH_INVALID: xrPathToString(path == XR_NULL_PATH)

One complaint I have is that the checkbox doesn't really look like a checkbox, but like a buggy RadioButton.

I tried removing the radius, height, and width properties, but testing will take a while because I have to recompile libnode.

[JulianGro]

As always, GitHub isn't rendering the suggestions properly on my end, so chances are something isn't right there. The suggestion is to remove the boxRadiuss.

[JulianGro]

Tested on Quest 2 with WiVRn and Valve Index with SteamVR.
On the Quest 2 it gets a little confusing, because the Quest's hand tracking will emulate controller inputs when hand tracking is disabled in Overte.
I haven't retested the Quest 1 yet, but my guess is that the Quest 1 doesn't emulate a controller if hand tracking is disabled.
I tested it on the Quest 2 as well now. The log messages are clean there too now:

[09/17 14:23:35] [INFO] [openxr.context] Controller 0 was disconnected
[09/17 14:23:35] [INFO] [openxr.context] Controller 1 was disconnected
(…)
[09/17 14:23:46] [INFO] [openxr.context] Controller 0: Interaction profile changed to '/interaction_profiles/oculus/touch_controller'
[09/17 14:23:46] [INFO] [openxr.context] Controller 1: Interaction profile changed to '/interaction_profiles/oculus/touch_controller'
(…)
[09/17 14:23:51] [INFO] [openxr.context] Controller 0 was disconnected
[09/17 14:23:51] [INFO] [openxr.context] Controller 1 was disconnected
[09/17 14:24:06] [INFO] [openxr.context] Controller 0: Interaction profile changed to '/interaction_profiles/oculus/touch_controller'
[09/17 14:24:06] [INFO] [openxr.context] Controller 1: Interaction profile changed to '/interaction_profiles/oculus/touch_controller'