Maintenance: split each provider in a package

- Fix VyprVPN port
- Fix missing Auth overrides

internal/provider/privatevpn/provider.go

@@ -0,0 +1,19 @@
+package privatevpn
+
+import (
+	"math/rand"
+
+	"github.com/qdm12/gluetun/internal/models"
+)
+
+type Privatevpn struct {
+	servers    []models.PrivatevpnServer
+	randSource rand.Source
+}
+
+func New(servers []models.PrivatevpnServer, randSource rand.Source) *Privatevpn {
+	return &Privatevpn{
+		servers:    servers,
+		randSource: randSource,
+	}
+}