[MM-63556] mmctl: Add compliance export download cmd (#30576)

* add mmctl compliance export download command and tests

- Introduced `ComplianceExportDownloadCmd` to facilitate downloading compliance export files.
- Implemented the `DownloadComplianceExport` method in the Client interface for handling file downloads.
- Added unit tests for the download command, covering successful downloads, error handling for non-existent jobs, and retries on failure.
- Included end-to-end tests to validate the command's functionality.
- Updated documentation to include usage examples and options for the new command.

* don't know why this was left out

* PR comments

* adjust test for new retry logic

* refactored download fn for compliance_export and export

* fix test due to fixed logic

* docs

server/cmd/mmctl/docs/mmctl_compliance-export.rst

@@ -38,6 +38,7 @@ SEE ALSO
 
 * `mmctl <mmctl.rst>`_ 	 - Remote client for the Open Source, self-hosted Slack-alternative
 * `mmctl compliance-export cancel <mmctl_compliance-export_cancel.rst>`_ 	 - Cancel compliance export job
+* `mmctl compliance-export download <mmctl_compliance-export_download.rst>`_ 	 - Download compliance export file
 * `mmctl compliance-export list <mmctl_compliance-export_list.rst>`_ 	 - List compliance export jobs, sorted by creation date descending (newest first)
 * `mmctl compliance-export show <mmctl_compliance-export_show.rst>`_ 	 - Show compliance export job