chore(constants): remove and move constant paths

- Remove unused paths
- Move paths to inline constants if used only once

internal/configuration/sources/files/openvpn.go

@@ -4,16 +4,22 @@ import (
 	"fmt"
 
 	"github.com/qdm12/gluetun/internal/configuration/settings"
-	"github.com/qdm12/gluetun/internal/constants"
+)
+
+const (
+	// OpenVPNClientKeyPath is the OpenVPN client key filepath.
+	OpenVPNClientKeyPath = "/gluetun/client.key"
+	// OpenVPNClientCertificatePath is the OpenVPN client certificate filepath.
+	OpenVPNClientCertificatePath = "/gluetun/client.crt"
 )
 
 func (r *Reader) readOpenVPN() (settings settings.OpenVPN, err error) {
-	settings.ClientKey, err = ReadFromFile(constants.ClientKey)
+	settings.ClientKey, err = ReadFromFile(OpenVPNClientKeyPath)
 	if err != nil {
 		return settings, fmt.Errorf("cannot read client key: %w", err)
 	}
 
-	settings.ClientCrt, err = ReadFromFile(constants.ClientCertificate)
+	settings.ClientCrt, err = ReadFromFile(OpenVPNClientCertificatePath)
 	if err != nil {
 		return settings, fmt.Errorf("cannot read client certificate: %w", err)
 	}