Bring back Delete function for Design submissions

[jmgasper]

Describe the bug
On manage submission page, the designers are missing the delete functionality and have to email support.

To Reproduce

• Login with a test account (like jgasperMobile12 / Appirio123)
• Register for a design challenge (like https://www.topcoder-dev.com/challenges/832c034a-d09a-43b9-9bdd-1efff6dbb485)
• Make a submission
• View the manage submissions page (https://topcoder-dev.com/challenges/{challengeID}/my-submissions)

Expected behavior
A button to delete a submission should be visible. This was working previously and now isn't. We need to do two things:

1. Identify the git checkin that broke this (please provide the commit hash)
2. Fix the issue through a git patch file

Screenshots