Mullvad updater (#228)

* Add Mullvad to updater cli
* Update hardcoded servers for Mullvad

internal/updater/mullvad_test.go

@@ -0,0 +1,31 @@
+package updater
+
+import (
+	"net"
+	"strings"
+	"testing"
+
+	"github.com/qdm12/gluetun/internal/models"
+	"github.com/stretchr/testify/assert"
+)
+
+func Test_stringifyMullvadServers(t *testing.T) {
+	servers := []models.MullvadServer{{
+		Country: "webland",
+		City:    "webcity",
+		ISP:     "not nsa",
+		Owned:   true,
+		IPs:     []net.IP{{1, 1, 1, 1}},
+		IPsV6:   []net.IP{{1, 1, 1, 1}},
+	}}
+	expected := `
+func MullvadServers() []models.MullvadServer {
+	return []models.MullvadServer{
+		{Country: "webland", City: "webcity", ISP: "not nsa", Owned: true, IPs: []net.IP{{1, 1, 1, 1}}, IPsV6: []net.IP{{1, 1, 1, 1}}},
+	}
+}
+`
+	expected = strings.TrimPrefix(strings.TrimSuffix(expected, "\n"), "\n")
+	s := stringifyMullvadServers(servers)
+	assert.Equal(t, expected, s)
+}