HDDS-12054. Move ozone debug prefix to ozone debug om prefix

[sarvekshayr]

What changes were proposed in this pull request?

The prefix subcommand only works on OM using the FSO namespace so it should be under the om subcommand.

What is the link to the Apache JIRA

HDDS-12054

How was this patch tested?

Tested the patch on a docker cluster and through TestOzoneFileSystemPrefixParser.java

bash-5.1$ ozone debug om
Missing required subcommand
Usage: ozone debug om [COMMAND]
Runs OM related subcommands.
Commands:
  prefix  Parse prefix contents

bash-5.1$ ozone debug om prefix
Missing required options: '--db=<dbPath>', '--path=<filePath>', '--bucket=<bucket>', '--volume=<volume>'
Usage: ozone debug om prefix --bucket=<bucket> --db=<dbPath> --path=<filePath>
                             --volume=<volume>
Parse prefix contents
      --bucket=<bucket>   bucket name
      --db=<dbPath>       Database File Path
      --path=<filePath>   prefixFile Path
      --volume=<volume>   volume name

[Tejaskriya]

Thanks for the patch @sarvekshayr. Overall LGTM, just a small suggestion below

[adoroszlai]

Thanks @sarvekshayr for the patch, @Tejaskriya for the review.