Maint: configuration Openvpn selection structure

- Move network protocol from ServerSelection to OpenVPNSelection child
- Move PIA encryption preset from ServerSelection to OpenVPNSelection child
- Move custom port from ServerSelection to OpenVPNSelection child

internal/provider/privateinternetaccess/connection.go

@@ -10,11 +10,11 @@ import (
 func (p *PIA) GetOpenVPNConnection(selection configuration.ServerSelection) (
 	connection models.OpenVPNConnection, err error) {
 	protocol := constants.UDP
-	if selection.TCP {
+	if selection.OpenVPN.TCP {
 		protocol = constants.TCP
 	}
 
-	port, err := getPort(selection.TCP, selection.EncryptionPreset, selection.CustomPort)
+	port, err := getPort(selection.OpenVPN)
 	if err != nil {
 		return connection, err
 	}

internal/provider/privateinternetaccess/filter.go

@@ -14,8 +14,8 @@ func (p *PIA) filterServers(selection configuration.ServerSelection) (
 			utils.FilterByPossibilities(server.Region, selection.Regions),
 			utils.FilterByPossibilities(server.Hostname, selection.Hostnames),
 			utils.FilterByPossibilities(server.ServerName, selection.Names),
-			selection.TCP && !server.TCP,
-			!selection.TCP && !server.UDP:
+			selection.OpenVPN.TCP && !server.TCP,
+			!selection.OpenVPN.TCP && !server.UDP:
 		default:
 			servers = append(servers, server)
 		}

internal/provider/privateinternetaccess/port.go

@@ -4,20 +4,21 @@ import (
 	"errors"
 	"fmt"
 
+	"github.com/qdm12/gluetun/internal/configuration"
 	"github.com/qdm12/gluetun/internal/constants"
 )
 
-func getPort(tcp bool, encryptionPreset string, customPort uint16) (
+func getPort(openvpnSelection configuration.OpenVPNSelection) (
 	port uint16, err error) {
-	if customPort == 0 {
-		return getDefaultPort(tcp, encryptionPreset), nil
+	if openvpnSelection.CustomPort == 0 {
+		return getDefaultPort(openvpnSelection.TCP, openvpnSelection.EncPreset), nil
 	}
 
-	if err := checkPort(customPort, tcp); err != nil {
+	if err := checkPort(openvpnSelection.CustomPort, openvpnSelection.TCP); err != nil {
 		return 0, err
 	}
 
-	return customPort, nil
+	return openvpnSelection.CustomPort, nil
 }
 
 func getDefaultPort(tcp bool, encryptionPreset string) (port uint16) {