This change implements the ability to get and set the WiFi back-end,
by leveraging a new script created for that purpose.
The idea is to be able to use 'wpa_supplicant' (which is the default
back-end in NetworkManager upstream) when 'iwd' (the default in
SteamOS) does not work for some reason.
This change interacts with another feature of steamos-manager, which
is to set debug mode for WiFi. Handling debug mode complicates things
substantially because those methods write config for 'iwd' and restart
the daemons/systemd units, with many interdependencies.
Instead of trying to implement all at once and attempt feature-parity
between back-ends on this aspect from the start, as a first step the
operations are just declared incompatible. As a result, if
WifiDebugMode=on the back-end cannot be changed, and conversely the
WifiDebugMode cannot be turned on when the back-end is
'wpa_supplicant'.
Co-authored-by: Manuel A. Fernandez Montecelo <mafm@igalia.com>
