Editing Network Interfaces should be possible without recreating them

[mbfm]

Currently, it is not possible to change the values of a network interface in LEA without deleting it and recreating it.
This is particularly cumbersome, because it also requires deleting and recreating the device with which this network interface is associated.

Alternatively, it might also make the process somewhat less cumbersome to allow devices to not be connected to any network interface, which is a change we would've liked to make a long time ago already.

Tasks:

• Come up with a design that allows editing and saving interfaces.
  Potentially, we could offer an Edit-button next to the respective table entry, which removes it from the table and populates the fields for creating an interface with those values.
• Implement this design.