api: add SSLCertificate to TransferEndpoint in content library API

Add the optional SSLCertificate field to TransferEndpoint in content
library API so it can be specified to probe remote transfer endpoint or
upload file from remote endpoint by pull. The field is already in the
ProbeResult as an optional field.

Closes: #3420

vapi/library/library_item_updatesession_file.go

@@ -1,5 +1,5 @@
 /*
-Copyright (c) 2019-2023 VMware, Inc. All Rights Reserved.
+Copyright (c) 2019-2024 VMware, Inc. All Rights Reserved.
 
 Licensed under the Apache License, Version 2.0 (the "License");
 you may not use this file except in compliance with the License.
@@ -31,6 +31,7 @@ import (
 // TransferEndpoint provides information on the source of a library item file.
 type TransferEndpoint struct {
 	URI                      string `json:"uri,omitempty"`
+	SSLCertificate           string `json:"ssl_certificate,omitempty"`
 	SSLCertificateThumbprint string `json:"ssl_certificate_thumbprint,omitempty"`
 }
 
@@ -107,7 +108,11 @@ func (c *Manager) AddLibraryItemFileFromURI(ctx context.Context, sessionID, name
 		if err != nil {
 			return nil, err
 		}
-		source.SSLCertificateThumbprint = res.SSLThumbprint
+		if res.SSLCertificate != "" {
+			source.SSLCertificate = res.SSLCertificate
+		} else {
+			source.SSLCertificateThumbprint = res.SSLThumbprint
+		}
 	}
 
 	return c.AddLibraryItemFile(ctx, sessionID, file)