Allow submitting authors to reassign a project to a different submitting author

[Tom Pollard]

Currently the submitting author of a project cannot be changed. We should consider updating the system to allow submitting author for a project to be switched (in a similar way to project reviewers).

Options:

1. Enable switching by project administrators, via the console.
2. Enable switching by submitting authors.

Perhaps begin with 1 and then introduce 2 later.