Allow access to Dependency list to members of a custom role

What does this MR do and why?

This change ensures that members of a custom role with the :read_dependency permission are allowed to view the Explore / Dependency list page. It looks like no code changes are needed because when a custom permission is applied through a custom role this action updates the users' project authorizations. I would like to preserve this behavior by submitting the tests included in this MR.

#438748 (closed)

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Screenshots or screen recordings

Before	After
	Same as before but with more tests. 😄

How to set up and validate locally

1. In rails console enable the experiment fully

   Feature.enable(:explore_dependencies)

2. Create a custom role with the :read_dependency permission enabled.
3. Assign role to a new or existing user.
4. Log in as the target user.
5. Visit http://127.0.0.1:3000/explore/dependencies