Don't display the add project link/button if the user does not have the project.create permission

[seav]

Currently^†, any logged-in user can click the add project link/button and this displays a three-page project creation wizard. It is only after going through all three pages that the user is given a permission denied error if the user does not actually have the project.create action permission.

It would be better in terms of UX if the link/button is hidden if the user does not have this permission in the first place or immediately given the permission denied error when accessing the first page of the wizard.

^† But only if the database has organizations:

context['add_allowed'] = Organization.objects.count() > 0

[clash99]

Same thought should apply to adding a new location to a project. Instead of messaging after the fact, we should hid the button from users that aren't eligible for that action.