[implemented] Collapsable groups in the front-end.

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I am trying to organize my rules and devices the best I can and I would really appreciate if the “groups” could be collapsed, to me that would be cleaner and easier to navigate.

Collapsable groups would be very very nice.
I will look into the code if I can implement this feature.
I hope, that I understand how the gui works.
Maybe someone could help me with that. It shouldn’t be that hard.

I implemented this in the mobile-frontend v0.8.76.

very nice