netifd: iprule add sport and dport

netifd: iprule add sport and dport

Maintainer: @nbd, @robimarko

I was missing the ip rules for `sport` and `dport` in netifd and although I have a working C knowledge, I have little netlink knowledge and it is the first time I looked into netifd but after some research I could come up with a working patch to implement `option sport` and `option dport`.

I hope you can have a look and implement these useful options.

Run tested: Dynalink DL-WRX36 (ipq8074) running Main Snapshot r29276-963d320086 20-apr-2025

Example 1 sport:
```
config rule
	option src '192.168.9.23/32'
	option sport '1194'
	option lookup 'main'
```
Result:
```
root@DL-WRX36:~# ip ru
0:      from all lookup local
1:      from 192.168.9.23 sport 1194 lookup main
```

Example 2  sport range:
```
config rule
	option src '192.168.9.23/32'
	option sport '1194-1195'
	option lookup 'main'
```
Result:
```
root@DL-WRX36:~# ip ru
0:      from all lookup local
1:      from 192.168.9.23 sport 1194-1195 lookup main
```

Example 3 dport:
```
config rule
	option src '192.168.9.23/32'
	option dport '1294'
	option lookup 'main'
```
Result:
```
root@DL-WRX36:~# ip ru
0:      from all lookup local
1:      from 192.168.9.23 dport 1294 lookup main
```

Example 4  dport range:
```
config rule
	option src '192.168.9.23/32'
	option dport '1294-1295'
	option lookup 'main'
```
Result:
```
root@DL-WRX36:~# ip ru
0:      from all lookup local
1:      from 192.168.9.23 dport 1294-1295 lookup main
```
Example 5 sport dport:
```
config rule
	option src '192.168.9.23/32'
	option sport '1194-1195'
	option dport '1294-1295'
	option lookup 'main'
```
Result:
```
root@DL-WRX36:~# ip ru
0:      from all lookup local
1:      from 192.168.9.23 sport 1194-1195 dport 1294-1295 lookup main
```

Signed-off-by: Erik Conijn <[email protected]>
Link: https://github.com/openwrt/netifd/pull/47
Signed-off-by: Robert Marko <[email protected]>