Description of problem:

While exporting the content in Satellite-6.10 using "# hammer content-export" command, there should be a pre-check performed which should check if "/var/lib/pulp/exports/" has sufficient space available for the export to be successful. This pre-check should be performed before export process is started and should give a warning or error beforehand instead of getting failed at the end.

Version-Release number of selected component (if applicable): Satellite-6.10

Steps to Reproduce:
1. Ensure "/var/lib/pulp/exports/" has very less disk space available.
2. Initiate a complete library synchronization using command "# hammer content-export complete library --organization-id 1".

Actual results: The export process is started and disk space check for "/var/lib/pulp/exports/" is not performed. The command later fails when "/var/lib/pulp/exports/" gets full in between the export process.

Expected results: A pre-check should be performed to ensure enough disk space is available in "/var/lib/pulp/exports/" before starting the export process after running "# hammer content-export" command.