Provide the ability to generate MD5 Checksum on space/site backup file

Problem Definition

When we perform a space/site export, there's no way to run the integrity checking on the downloaded file. This is crucial especially when handling the large backup files (eg: >1GB).

Suggested Solution

Provide the ability to generate the MD5 checksum from Confluence.

Why this is important

• Reduce the time in troubleshooting the backup file for migration.
  • Example: After spending hours to upload the backup into another instance, then Confluence is telling the file cannot be processed due to the corrupted backup file. With MD5 checksum, we can validate the downloaded file before running the restoration.
• Make sure we get the working backup file for future use.
  • Example: We generate the backup file in case of disaster recovery purpose or before we delete a space/site. It's not good to find out the backup file is actually corrupted after months, when we would like to restore the space/site.