Draft submissions should not be visible to challenge managers

[stepchud]

On Phoenix, draft submissions from solvers are not available to admins or challenge managers. Submissions on Rails are not filtering out draft submissions and so the counter_cache column phases.submissions_count includes draft submissions in the count and also the phase submissions list displays them. Draft Submissions can be assigned to evaluators, etc.

How to reproduce

Create Submission

1. As a Solver, create a draft submission for a challenge phase, via the normal web submission page.
2. As a Challenge Manager, try to manage your "Submissions & Evaluations"

Expected behavior

• Draft submissions should not be factored into submission counts and challenge managers should not be able to see them listed in their Phase Submissions view. Evaluators should not be able to be assigned to draft submissions.

Actual behavior

submissions_count includes drafts and the draft submissions are visible on the app.

Technical Notes

Phoenix routes

• Web.SubmissionController.create/2 ("action" => "draft") ("action" => "review")
• Web.SubmissionController.update/2 ("action" => "review" to submit)
• Web.SubmissionController.delete
• The route at Web.SubmissionController.submit/2 and view functions Web.SubmissionView.submit_button/4, Web.SubmissionView.submit_button2/4 seem to be dead code.

[stepchud]

@r-bartlett-gsa this is ready to test, it is similar to #370 except it only applies to Draft Submission status.