Move tls generation functions and data into own package

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.

goKMS/kms/tls/tls.go

+package kmstls
+
+import (
+	"crypto/tls"
+	"crypto/x509"
+	"fmt"
+	"os"
+
+	"google.golang.org/grpc/credentials"
+)
+
+type TlsData struct {
+	TLS      bool
+	CaFile   string
+	CertFile string
+	KeyFile  string
+}
+
+func GenerateGRPCServerTransportCredsWithTLS(caFilePath, certFile, keyFile string) (credentials.TransportCredentials, error) {
+	cp := x509.NewCertPool()
+	b, err := os.ReadFile(caFilePath)
+	if err != nil {
+		return nil, err
+	}
+
+	if !cp.AppendCertsFromPEM(b) {
+		return nil, fmt.Errorf("credentials: failed to append certificates")
+	}
+
+	cert, err := tls.LoadX509KeyPair(certFile, keyFile)
+	if err != nil {
+		return nil, err
+	}
+
+	tlsConfig := &tls.Config{
+		MinVersion:   tls.VersionTLS13,
+		ClientCAs:    cp,
+		Certificates: []tls.Certificate{cert},
+		ClientAuth:   tls.RequireAndVerifyClientCert,
+	}
+
+	return credentials.NewTLS(tlsConfig), nil
+}
+
+func GenerateGRPCClientTransportCredsWithTLS(caFilePath, certFile, keyFile string) (credentials.TransportCredentials, error) {
+	cp := x509.NewCertPool()
+
+	b, err := os.ReadFile(caFilePath)
+	if err != nil {
+		return nil, err
+	}
+	if !cp.AppendCertsFromPEM(b) {
+		return nil, fmt.Errorf("credentials: failed to append certificates")
+	}
+
+	cert, err := tls.LoadX509KeyPair(certFile, keyFile)
+	if err != nil {
+		return nil, err
+	}
+
+	tlsConfig := &tls.Config{
+		MinVersion:   tls.VersionTLS13,
+		RootCAs:      cp,
+		Certificates: []tls.Certificate{cert},
+	}
+
+	return credentials.NewTLS(tlsConfig), nil
+}