Maintenance: split each provider in a package

- Fix VyprVPN port
- Fix missing Auth overrides

internal/provider/utils/pick.go

@@ -0,0 +1,12 @@
+package utils
+
+import (
+	"math/rand"
+
+	"github.com/qdm12/gluetun/internal/models"
+)
+
+func PickRandomConnection(connections []models.OpenVPNConnection,
+	source rand.Source) models.OpenVPNConnection {
+	return connections[rand.New(source).Intn(len(connections))] //nolint:gosec
+}