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/vpnunlimited/connection.go

@@ -15,7 +15,7 @@ func (p *Provider) GetOpenVPNConnection(selection configuration.ServerSelection)
 	connection models.OpenVPNConnection, err error) {
 	const port = 1194
 	const protocol = constants.UDP
-	if selection.TCP {
+	if selection.OpenVPN.TCP {
 		return connection, ErrProtocolUnsupported
 	}
 

internal/provider/vpnunlimited/filter.go

@@ -16,8 +16,8 @@ func (p *Provider) filterServers(selection configuration.ServerSelection) (
 			utils.FilterByPossibilities(server.Hostname, selection.Hostnames),
 			selection.FreeOnly && !server.Free,
 			selection.StreamOnly && !server.Stream,
-			selection.TCP && !server.TCP,
-			!selection.TCP && !server.UDP:
+			selection.OpenVPN.TCP && !server.TCP,
+			!selection.OpenVPN.TCP && !server.UDP:
 		default:
 			servers = append(servers, server)
 		}