puppet nftables

Fix IPv4 source address type detection

Before this patch, a rule like this:

```
nftables::simplerule { 'foo':
action => 'accept',
dport => 443,
proto => 'tcp4',
saddr => '192.168.1.10',
}
```

would incorrectly generate this rule:...

Relax type validation in template

It comes already validated from the calling class.

Encapsulate addr-related exprs in Nftables::Addr

Sort template parameters alphabetically

Implement nftables::simplerule::sport

Implement nftables:;simplerule::counter

Allow IPv4 and IPv6 only rules

Add nftables::simplerule