recognise NetworkManager's Wireguard connections as VPN connections

Feature summary

Provide a similar user experience for Wireguard connections as GNOME currently offers for OpenVPN connections

Currently, with OpenVPN connections:

• they can be easily configured via GNOME Settings -> Network, there's even a "VPN" section

• within that "VPN" section, they are listed with a toggle button to activate / deactivate

• within GNOME's top-right menu there is a VPN item to provide convenient ways to toggle

• within GNOME's top-right status area there is a visual indicator to show that a VPN connection is active (appears between the network status icon and the volume status icon)

But none of this is available for Wireguard connections as of GNOME 3.36.4, it would be terrific to offer it

How would you like it to work

All the OpenVPN GNOME features I listed above ought to be similar for Wireguard connections

Relevant links, screenshots, screencasts etc.

• guide I have followed to add a Wireguard connection to NetworkManager: https://blogs.gnome.org/thaller/2019/03/15/wireguard-in-networkmanager/

• previous discussion about changing the layout of the top-right menus: #1460

• buggy/broken extension that provides a visual indicator: https://extensions.gnome.org/extension/2488/wireguard-appindicator/

• existing issue open for work remaining in GNOME Settings: gnome-control-center#982 (closed)