Non-admin user cannot connect to new WiFi networks

[Rudra Trivedi]

An admin password is required to connect to new Wifi networks.
This is through both quick-settings(gnome-shell) and the Settings(gnome-control-center) app.

Steps to reproduce:

 - Set up Ubuntu Desktop as normal
 - Create a new standard user
 - Login as the new user and try to connect to a new WiFi network
 - Error: "System policy prevents modification of network settings for all users"

1) The release of Ubuntu you are using, via 'lsb_release -rd' or System -> About Ubuntu

Description: Ubuntu 24.04 LTS
Release: 24.04

2) The version of the package you are using, via 'apt-cache policy pkgname' or by checking in Software Center

gnome-shell:
  Installed: 46.0-0ubuntu5.1
  Candidate: 46.0-0ubuntu5.1

3) What you expected to happen

A standard(non-admin) user should be able to create new WiFi connections
(This probably extends to all types of connections like VPN, but I haven't tested it)

4) What happened instead

The standard user is prompted for admin credentials to connect to new Wifi networks.

The original report by Jan Schär (@jschaer) says gnome-control-center allowed to create `personal` connections, but this does not seem to be true for at least Noble.

Upstream report:

When connecting to a new WiFi in the gnome-shell quick settings as a non-admin user, an admin password is requested ("System policy prevents modification of network settings for all users"). However, connecting to a WiFi in gnome-control-center works without an admin password, and a connection is created only for the current user.

Here is the logic for this in gnome-control-center:
https://gitlab.gnome.org/GNOME/gnome-control-center/-/blob/e6978a480110ad5e24d3b34107675eb03fa3cc31/panels/network/net-device-wifi.c#L491-506

This logic is missing in gnome-shell:
https://gitlab.gnome.org/GNOME/gnome-shell/-/blob/8a048190b99c7d34a319f41f0a980e388a0ba86e/js/ui/status/network.js#L963

I think gnome-shell should do the same as gnome-control-center is doing, and create a non-shared connection if there is no permission to create a shared one.

(from https://gitlab.gnome.org/GNOME/gnome-shell/-/issues/7378)