Enable users to select public projects they are not members of

`frontend/vre/globals/projects.js` currently fetches two collections of projects:

- `myProjects`, which, as the name suggests, contains projects that the user is a member of, and
- `allProjects`, which contains all projects that are also in `myProjects` plus all projects that are public. In other words, all projects *that the user can view*.

This module also creates the singleton instance of `ProjectMenuView`, which lets the user select the current project. That view currently has `myProjects` as its `.collection`, so that users can only select projects that they have write access to.

After #319, users will only be able to view collections within the currently selected project. This means that they must be able to select public projects that they are not members of in order to keep access to the collections within those projects.

In summary: **change `projectMenu.collection` to be `allProjects`**.