Maintenance: refactor servers updater code

- Require at least 80% of number of servers now to pass
- Each provider is in its own package with a common structure
- Unzip package with unzipper interface
- Openvpn package with extraction and download functions

internal/updater/providers/vyprvpn/filename.go

@@ -0,0 +1,22 @@
+package vyprvpn
+
+import (
+	"errors"
+	"fmt"
+	"strings"
+)
+
+var errNotOvpnExt = errors.New("filename does not have the openvpn file extension")
+
+func parseFilename(fileName string) (
+	region string, err error,
+) {
+	const suffix = ".ovpn"
+	if !strings.HasSuffix(fileName, suffix) {
+		return "", fmt.Errorf("%w: %s", errNotOvpnExt, fileName)
+	}
+
+	region = strings.TrimSuffix(fileName, suffix)
+	region = strings.ReplaceAll(region, " - ", " ")
+	return region, nil
+}