Change i18n key for Store link in admin header

spree_i18n translates the "store" key in different ways, sometimes like
"shop" and sometimes like "save". This could be because of a clash in
usage between Spree add-ons.

To be more specific, the "Store" link in the admin section now uses the
"admin.header.store" translation key.

app/views/spree/layouts/admin/_login_nav.html.haml

@@ -11,4 +11,4 @@
       = link_to t(:logout), spree.logout_path
     %li{"data-hook" => "store-frontend-link"}
       %i.icon-external-link
-      = link_to t(:store), spree.root_path, :target => '_blank'
+      = link_to t(".header.store"), spree.root_path, target: "_blank"

config/locales/en.yml

@@ -2589,6 +2589,10 @@ See the %{link} to find out more about %{sitename}'s features and to start using
     my_account: "My account"
     date: "Date"
     time: "Time"
+    layouts:
+      admin:
+        header:
+          store: Store
     admin:
       orders:
         invoice: