[Xperia 10 III] Add camera switch multiCameraEnable=TRUE/FALSE

[moorchegue]

On Sony Xperia 10 III there's currently no way to use all 3 rear cameras together with the front one. There's a workaround described here: sonyxperiadev/bug_tracker#732 and here: https://docs.sailfishos.org/Support/Help_Articles/Camera/#multiple-cameras-of-xperia-10-iii

But it's quite cumbersome and nobody would be able to do it when they need to switch between modes in real world scenarios. While there's no permanent bug fix it'd help a lot if there was a UI switch, and Utilities is probably a good place for it?

Perhaps could do some sed under the hood to update the value and then restart the cam service?