Show alert if user todos are hidden due to expired SSO session

What does this MR do and why?

Describe in detail what your merge request does and why.

Resolves https://gitlab.com/gitlab-org/gitlab/-/issues/389379

When a user is a member of a group with SAML SSO for GitLab.com enabled, and hasn't visited a group-level page within the last 24 hours, todos related to that group may be hidden.

While this may not be the ideal long-term solution it is a clear notice to the user that they may have hidden todos and need to re-authenticate to see those todos. The listed groups are only present if the todos point to an object/target in that group hierarchy.

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How to set up and validate locally

Numbered steps to set up and validate the change are strongly suggested.

How to short circuit to show the UI even when re-auth isn't necessary.

1. Modify ee/lib/gitlab/auth/group_saml/sso_enforcer.rb and add a return of true to the access_restricted_groups method:

       # Given an array of groups or subgroups, return an array
       # of root groups that are access restricted for the user
       def self.access_restricted_groups(groups, user: nil)
         return [] unless groups&.any?
   
         ::Preloaders::GroupRootAncestorPreloader.new(groups, [:saml_provider]).execute
         root_ancestors = groups.map(&:root_ancestor).uniq
   
         root_ancestors.select do |root_ancestor|
           group_access_restricted?(root_ancestor, user: user, for_project: true)
           true # <-------- ADD THIS HERE 
         end
       end

2. Refresh/visit /dashboard/todos and the alert should appear.

MR acceptance checklist

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