Improve add/remove to room plan

[roblom]

When for example autodiscovery adds a lot of devices I have to add them all one by one to the room plan. It would improve and save a lot of clicks when it is possible to at least be able to select several devices and add all selected to the room plan.
Or maybe it would be an even better improvement if it is possible to add devices also to a room plan in the devices overview. It is possible to filter on them but not possible to add or remove the devices to a room plan.

[McMelloW]

Not hindered by the amount of work this takes to program. I second this request also

[waltervl]

No mass room assignment but this PR to be implemented soon (if approved) will make it easier as you can assign devices from the device edit form https://github.com/domoticz/domoticz/pull/6035