Issue 585: Ensure that users cannot be added to "New" / "Inactive" / "Archived" projects

Check whether users can be added to a Project with the "New", "Inactive", or "Archived" statuses:

"Can a user request to join such a project from the UI?"
- A user cannot access a Project that is "New," "Inactive," or "Archived" from the "Join a Project" page. Only "Active" Projects are listed.
- Users also cannot access "New," "Inactive," or "Archived" Projects by going to /project/##, where ## represents the project ID of a Project.
"Can a PI/manager of such a project add users to such a project?"
- For a "New" Project, no. The PI of a "New" Project can access the "Add a User" button and go through the flow of adding a user, however upon submission, the following error message shows: Project does not have a LBL Project ID for billing. You cannot add users until one is set.
- For an "Inactive" Project, yes. The PI can access the "Add a User" button and successfully add a user. This probably should not be allowed.
- For an "Archived" Project, no. The PI cannot make any changes to an "Archived" Project.

Changes

In the project_detail template, added logic that makes the 'Add User' button functional only if the project's status is 'Active'. Otherwise, the button is disabled.
- However, this only disables the UI button for a PI/manager to access the page at /add-users-search to add users. Manually inserting this into the URL would still allow a PI/manager to visit the page and successfully add a user to an "Inactive" Project.
To fix the above problem, updated ProjectAddUsersSearchView to disallow accessing /add-users-search to add users to a non-active project. Initially, this only applied to "Archived" Projects.
- Attempting to access /add-users-search for any Project that is not "Active" will display a banner that says, "You cannot add users to a [new, inactive, archived] project."

ucb-rit / coldfront