fix(column): full redraw with 'stc, 'rnu' and inserted lines (#27712)

Problem:  Text is not redrawn with 'relativenumber' when only the 'statuscolumn' is redrawn after inserted lines.
Solution: Force a full redraw if statuscolumn width changed.

test/functional/ui/statuscolumn_spec.lua

@@ -927,4 +927,17 @@ describe('statuscolumn', function()
                                        |
     ]])
   end)
+
+  it('line increase properly redraws buffer text with relativenumber #27709', function()
+    screen:try_resize(33, 4)
+    command([[set rnu nuw=3 stc=%l\ ]])
+    command('call setline(1, range(1, 99))')
+    feed('Gyyp')
+    screen:expect([[
+      98  98                           |
+      99  99                           |
+      100 ^99                           |
+                                       |
+    ]])
+  end)
 end)