Config resync instead of restart

In the wg.conf monitor service a resync can be issued instead of a full restart.

https://github.com/ngoduykhanh/wireguard-ui/pull/316

Pseudocode

```bash
if interface_checksum_matches; then
  sync config
else
  restart interface
fi
```

awk script

```awk
$1 ~ /^\[Interface\]$/ { out=1; }; out != 1 { next; }; $1 ~ /^[^\[#]/ { print; next}; { exit }
```