net: ipv6 support, merge unix+ip;[pack:x] attribute (#9904)

examples/net_resolve.v

@@ -0,0 +1,24 @@
+import net
+
+for addr in [
+	'vlang.io:80',
+	'google.com:80',
+	'steampowered.com:80',
+	'api.steampowered.com:80',
+] {
+	println('$addr')
+
+	for @type in [net.SocketType.tcp, .udp] {
+		family := net.AddrFamily.unspec
+
+		addrs := net.resolve_addrs(addr, family, @type) or {
+			println('> None')
+			continue
+		}
+
+		for a in addrs {
+			f := a.family()
+			println('> $a $f ${@type}')
+		}
+	}
+}