Feature/add to dashboard button

Purpose
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Currently, the only way to add projects to your Dashboard's Project Organizer is from within the project organizer. There are smart folders with your projects and registrations, and you can search for projects from within the info widget to add to folders, but if you are elsewhere in the OSF, it's a laborious process to get the project into the Organizer. This PR allows you to be on a project and add the current project to the Project Organizer.

Closes Issue https://github.com/CenterForOpenScience/openscienceframework.org/issues/1186

Changes
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Puts a button on the project header that adds the current project to the Dashboard folder of the user's Project Organizer. Disabled if the user is not logged in, if the folder is already in the dashboard folder of the user's project organizer, or if the user doesn't have permissions to view.

Side Effects
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Also fixes a minor issue with the watch button count being slow to update.

(Replaces https://github.com/CenterForOpenScience/osf/pull/1184https://github.com/CenterForOpenScience/osf/pull/1184 )
How can `auth` be `None` here if the `must_be_logged_in` decorator is used?