Prevent project duplication

[Apexal]

When a student wants to lead a project that they don't own, especially when it's an external project, they will attempt to create a new project despite the original one existing already. This results in an error when viewing the page and causes a break in the continuity of a project record.

We should have some mechanism for students to claim projects, with automatic suggestions to do so if they start entering the details of an already existing project.