Obtain PIA v4 server information from API (#257)

- Obtain CN for port forwarding https verification
- Obtain for each server if they support port forwarding
- Obtain for each server their IP address for openvpn UDP and openvpn TCP (one for each)
- Updater program updated to use API
- Hardcoded values updated for PIA v3 and v4 servers
- Clearer separation between pia v3 and v4
- Fixes #250

internal/models/servers.go

@@ -5,7 +5,7 @@ type AllServers struct {
 	Cyberghost CyberghostServers `json:"cyberghost"`
 	Mullvad    MullvadServers    `json:"mullvad"`
 	Nordvpn    NordvpnServers    `json:"nordvpn"`
-	PiaOld     PiaServers        `json:"piaOld"`
+	PiaOld     PiaOldServers     `json:"piaOld"`
 	Pia        PiaServers        `json:"pia"`
 	Purevpn    PurevpnServers    `json:"purevpn"`
 	Surfshark  SurfsharkServers  `json:"surfshark"`
@@ -28,6 +28,11 @@ type NordvpnServers struct {
 	Timestamp int64           `json:"timestamp"`
 	Servers   []NordvpnServer `json:"servers"`
 }
+type PiaOldServers struct {
+	Version   uint16         `json:"version"`
+	Timestamp int64          `json:"timestamp"`
+	Servers   []PIAOldServer `json:"servers"`
+}
 type PiaServers struct {
 	Version   uint16      `json:"version"`
 	Timestamp int64       `json:"timestamp"`