Add socket and cable support to the Monitors asset type

[mrcvnjk]

Description

We register displays with a physical RJ45 network connection under the default Monitors asset type.
In our GLPI installation, these monitors cannot be selected in the device list when configuring Sockets. As a result, we cannot document their physical network connections and associated cabling as required.

Requested functionality

Add socket support to the existing Monitors asset type. It should be possible to create a physical socket, such as an RJ45 socket, on a monitor and use Cables to connect it to another socket, for example on a network wall outlet or patch panel.
Monitors should become selectable in the relevant device lists. Existing monitor records should remain intact, without requiring users to recreate these devices as Peripherals or under a custom asset type.

Use case

A display with an RJ45 connection is connected to a network wall outlet. We would like to document this physical connection in GLPI and view it from both the monitor record and the associated socket.