Just as it happens for the `/etc/network/interfaces` it would be more polite to actually ask the user if they want to overwride their `/etc/NetworkManager/NetworkManager.conf`.
Changing this file by force will most likely shut a user out of their PI, because of wifi MAC address randomization, which is hardly the expected behavior from an install script.
__Those choosing to use this install script do it to keep control over their machine, which includes avoiding unexpected deletion of their config files.__
For instance, things work just fine for me with the following `NetworkManager.sh`:
```
[main]
plugins=ifupdown,keyfile
[ifupdown]
managed=false
[device]
wifi.scan-rand-mac-address=no
```
If something out of the downloaded `NetworkManager.sh` is actually mandatory (doesn't seem so tho) It's would be better di explicitly explain it to the user so their can take actions, rather than causing them unexpected behaviors.
A systemd service may be marked as enabled as vendor preset, and this
breaks the check we used to check if it was active.
Here's what you get in an Ubuntu 20.04 installation:
❯ sudo systemctl status ModemManager
● ModemManager.service - Modem Manager
Loaded: loaded (/lib/systemd/system/ModemManager.service; disabled; vendor preset: enabled)
Active: inactive (dead)
❯ systemctl list-unit-files ModemManager.service
UNIT FILE STATE VENDOR PRESET
ModemManager.service disabled enabled
1 unit files listed
While the list-unit-files can be filtered using `--state=enabled`, we
can just rely on `systemctl is-enabled` instead.
