refactor(tests): all screen tests should use highlights

This is the first installment of a multi-PR series significantly
refactoring how highlights are being specified.

The end goal is to have a base set of 20 ish most common highlights,
and then specific files only need to add more groups to that as needed.

As a complicating factor, we also want to migrate to the new default
color scheme eventually. But by sharing a base set, that future PR
will hopefully be a lot smaller since a lot of tests will be migrated
just simply by updating the base set in place.

As a first step, fix the anti-pattern than Screen defaults to ignoring
highlights. Highlights are integral part of the screen state, not
something "extra" which we only test "sometimes". For now, we still
allow opt-out via the intentionally ugly

  screen._default_attr_ids = nil

The end goal is to get rid of all of these eventually (which will be
easier as part of the color scheme migration)

test/functional/ui/screen.lua

@@ -139,6 +139,43 @@ local function _init_colors()
   end
   Screen.colors = colors
   Screen.colornames = colornames
+
+  Screen._global_default_attr_ids = {
+    [1] = { foreground = Screen.colors.Blue1, bold = true },
+    [2] = { reverse = true },
+    [3] = { bold = true, reverse = true },
+    [4] = { background = Screen.colors.LightMagenta },
+    [5] = { bold = true },
+    [6] = { foreground = Screen.colors.SeaGreen, bold = true },
+    [7] = { background = Screen.colors.Gray, foreground = Screen.colors.DarkBlue },
+    [8] = { foreground = Screen.colors.Brown },
+    [9] = { background = Screen.colors.Red, foreground = Screen.colors.Grey100 },
+    [10] = { background = Screen.colors.Yellow },
+    [11] = {
+      foreground = Screen.colors.Blue1,
+      background = Screen.colors.LightMagenta,
+      bold = true,
+    },
+    [12] = { background = Screen.colors.Gray },
+    [13] = { background = Screen.colors.LightGrey, foreground = Screen.colors.DarkBlue },
+    [14] = { background = Screen.colors.DarkGray, foreground = Screen.colors.LightGrey },
+    [15] = { foreground = Screen.colors.Brown, bold = true },
+    [16] = { foreground = Screen.colors.SlateBlue },
+    [17] = { background = Screen.colors.LightGrey, foreground = Screen.colors.Black },
+    [18] = { foreground = Screen.colors.Blue1 },
+    [19] = { foreground = Screen.colors.Red },
+    [20] = { background = Screen.colors.Yellow, foreground = Screen.colors.Red },
+    [21] = { background = Screen.colors.Grey90 },
+    [22] = { background = Screen.colors.LightBlue },
+    [23] = { foreground = Screen.colors.Blue1, background = Screen.colors.LightCyan, bold = true },
+    [24] = { background = Screen.colors.LightGrey, underline = true },
+    [25] = { foreground = Screen.colors.Cyan4 },
+    [26] = { foreground = Screen.colors.Fuchsia },
+    [27] = { background = Screen.colors.Red, bold = true },
+    [28] = { foreground = Screen.colors.SlateBlue, underline = true },
+    [29] = { foreground = Screen.colors.SlateBlue, bold = true },
+    [30] = { background = Screen.colors.Red },
+  }
 end
 
 --- @param width? integer
@@ -257,6 +294,10 @@ function Screen:attach(options, session)
   if self._options.ext_multigrid then
     self._options.ext_linegrid = true
   end
+
+  if self._default_attr_ids == nil then
+    self._default_attr_ids = Screen._global_default_attr_ids
+  end
 end
 
 function Screen:detach()
@@ -480,7 +521,10 @@ function Screen:expect(expected, attr_ids, ...)
       attr_state.id_to_index = self:linegrid_check_attrs(attr_state.ids or {})
     end
 
-    local actual_rows = self:render(not expected.any, attr_state)
+    local actual_rows
+    if expected.any or grid then
+      actual_rows = self:render(not expected.any, attr_state)
+    end
 
     if expected.any then
       -- Search for `any` anywhere in the screen lines.