* print resource list metadata in velero backup describe details
Signed-off-by: Adnan Abdulhussein <aadnan@vmware.com>

* rewrite TestGetDownloadURL to test more scenarios
Signed-off-by: Adnan Abdulhussein <aadnan@vmware.com>

* move backup printer helpers to backup_printer.go
Signed-off-by: Adnan Abdulhussein <aadnan@vmware.com>

* move describe printer helpers back to backup_describer

and rename to prefix with describe* to indicate that they are used for the describe command
Signed-off-by: Adnan Abdulhussein <aadnan@vmware.com>

* split backup and restore tests for TestGetDownloadURL
Signed-off-by: Adnan Abdulhussein <aadnan@vmware.com>

* friendlier error message when backup resource list missing
Signed-off-by: Adnan Abdulhussein <aadnan@vmware.com>