udev: split wifi and bt rules into two separate files, add systemd unit file, and add BT mac retry

The udev rule for bluetooth doesn't work on systemd[1], by splitting the rule into two separate rules, distros can leave this bluetooth rule out when packaging for systemd.

Distros packaging bootmac will have to make note of the new rule files/names.

This also includes a systemd unit file that can be used to autostart bootmac when bluetooth stuff is starting up (e.g. when the adapter is available), and provides a nicer way to add delays instead of trying to delay udev scripts, scripts that take 'too long' for udev can cause problems.

1. https://github.com/systemd/systemd/issues/35003

bootmac

@@ -204,13 +204,13 @@ mac_wlan() {
                 && ip link set dev "$WLAN_INTERFACE" address "$WLAN_MAC" ; then
             break
         fi
-        echo "Unable to set wlan MAC, retrying after 1 second..."
+        log "Unable to set wlan MAC, retrying after 1 second..."
         sleep 1
         timeout=$((timeout + 1))
     done
 
     if [ $timeout -ge "$WLAN_TIMEOUT" ]; then
-        echo "Failed to set wlan MAC address, command timed out after $WLAN_TIMEOUT seconds"
+        log "Failed to set wlan MAC address, command timed out after $WLAN_TIMEOUT seconds"
         return 1
     fi