Maintenance: split each provider in a package

- Fix VyprVPN port
- Fix missing Auth overrides

internal/provider/privateinternetaccess/provider.go

@@ -0,0 +1,23 @@
+package privateinternetaccess
+
+import (
+	"math/rand"
+	"time"
+
+	"github.com/qdm12/gluetun/internal/models"
+)
+
+type PIA struct {
+	servers      []models.PIAServer
+	randSource   rand.Source
+	timeNow      func() time.Time
+	activeServer models.PIAServer
+}
+
+func New(servers []models.PIAServer, randSource rand.Source, timeNow func() time.Time) *PIA {
+	return &PIA{
+		servers:    servers,
+		timeNow:    timeNow,
+		randSource: randSource,
+	}
+}