Adding tls support for akms-ckms client and server

Description

Related Issue

Motivation and Context

How Has This Been Tested?

Screenshots (if appropriate):

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)

Checklist:

• My code follows the code style of this project.
• My change requires a change to the documentation.
• I have updated the documentation accordingly.
• I have read the CONTRIBUTING document.
• I have added tests to cover my changes.
• All new and existing tests passed.

akms-simulator/akms-simulator.go

@@ -28,9 +28,9 @@ type KSAKey struct {
 }
 
 func main() {
-	tlsCAFile := flag.String("ca", "ca.crt", "Path to CA certificate file")
-	tlsCertFile := flag.String("cert", "cert.crt", "Path to certificate file")
-	tlsKeyFile := flag.String("key", "key.key", "Path to key file")
+	tlsCAFile := flag.String("ca", "", "Path to CA certificate file")
+	tlsCertFile := flag.String("cert", "", "Path to certificate file")
+	tlsKeyFile := flag.String("key", "", "Path to key file")
 	flag.Parse()
 
 	logrus.Info("Starting AKMS Simulator...")
@@ -45,7 +45,7 @@ func main() {
 		Handler: router,
 	}
 
-	if tlsCAFile != nil && tlsCertFile != nil && tlsKeyFile != nil {
+	if *tlsCAFile != "" && *tlsCertFile != "" && *tlsKeyFile != "" {
 		logrus.Info("TLS enabled")
 		cp := x509.NewCertPool()
 		b, err := os.ReadFile(*tlsCAFile)