network: Give NetworkManager control over USB gadgets

The default NM config excludes USB gadgets from being managed.

The gadget is a regular network interface, and letting it be managed by /etc/network results in confusion when NM resets DNS settings.
3 jobs for nm_usb in 4 minutes and 18 seconds (queued for 1 second)
latest
Status Job ID Name Coverage
  Build
passed #240780
librem5
build:deb

00:01:59

 
  Test
passed #240781
librem5
test:download:deb

00:01:47

passed #240782
librem5
test:download:pip

00:02:19