Add a new not-really-a-Next-button needle for gnome-initial-setup

In g-i-s 3.37.91, the first screen has a 'Start Setup' button
rather than a 'Next' button. Easiest thing for us to do here is
just to add a new needle which has the 'next_button' tag even
though it's clearly not a 'Next' button, because then the code
still works :) So do that, but give the file a suggestive name
and explain the situation in a code comment.

Signed-off-by: Adam Williamson <awilliam@redhat.com>

lib/utils.pm

@@ -629,6 +629,9 @@ sub gnome_initial_setup {
     # https://bugzilla.gnome.org/show_bug.cgi?id=794825
     @nexts = grep {$_ ne 'software'} @nexts;
 
+    # note: in g-i-s 3.37.91 and later, the first screen has a "Start
+    # Setup" button, not a "Next" button. For code simplicity, we just
+    # have a needle for that button which has the next_button tag
     assert_screen ["next_button", "auth_required"], $args{timeout};
     # workaround auth dialog appearing to change timezone even
     # though timezone screen is disabled

needles/gnome/next_button-startsetup-20200818.json

@@ -0,0 +1,16 @@
+{
+  "area": [
+    {
+      "height": 21,
+      "ypos": 673,
+      "xpos": 474,
+      "width": 74,
+      "type": "match"
+    }
+  ],
+  "properties": [],
+  "tags": [
+    "next_button",
+    "LANGUAGE-english"
+  ]
+}