feat(client): Add network config for ICMP endpoint client (#661)

* feat(client): Add network to config

* feat(client): Use network client config for pinger

* feat(client): Add client network configuration and demo to README

* feat(client): Add tests for pinger using network config

* feat(client): Drop integration tests

* feat(client): Add comment to tests

* feat(client): Add tests

* Update README.md

---------

Co-authored-by: TwiN <twin@linux.com>

client/config.go

@@ -30,6 +30,7 @@ var (
 		Insecure:       false,
 		IgnoreRedirect: false,
 		Timeout:        defaultTimeout,
+		Network:        "ip",
 	}
 )
 
@@ -64,6 +65,9 @@ type Config struct {
 	IAPConfig *IAPConfig `yaml:"identity-aware-proxy,omitempty"`
 
 	httpClient *http.Client
+
+	// Network (ip, ip4 or ip6) for the ICMP client
+	Network string `yaml:"network"`
 }
 
 // DNSResolverConfig is the parsed configuration from the DNSResolver config string.