Improve CILogon linked accounts readability

[lagoan]

After adding SSO with CILogon we show the credential ID on the users profile page in view

roadmap/app/views/devise/registrations/_external_openid_connect.html.erb

Line 13 in d4906c4

<%= id.value %>

.

We should change this to something more useful, such as the user's email as suggested by @aaronskiba

https://github.com/portagenetwork/roadmap/pull/872/files#r1747485592

[aaronskiba]

The below text/wording regarding "Institutional credentials" should be further considered too. CILogon does not limit the user to institutional credentials when linking an account.

<i class="fas fa-user" title="<%= _('Institutional credentials') %>" aria-hidden="true"></i>
        &nbsp;
        <%= link_to _('Link your institutional credentials'),
                    Rails.application.routes.url_helpers.send("user_openid_connect_omniauth_authorize_path"),
                    title: _("Link your institutional credentials to access your account with them."),
                    'data-toggle': "tooltip", method: :post %>

[aaronskiba]

Also, maybe a separate issue, but do we want the link account feature to redirect back to homepage? It might be best to stay on the profile page so the user can verify that the link was successful.