improve cliponaxis_false mock

- show off `(x|y)axis.layer`
- lock down behavior for `cliponaxis: true` traces
  on hasClipOnAxisFalse subplot
- add annotations for more descriptive mock

Author: etpinard

test/image/baselines/cliponaxis_false.png

@@ -21,7 +21,7 @@
         "opacity": 1
       },
       "text": "not<br>clipped",
-      "textposition": ["left", "left", "bottom", "right", "right", "top"],
+      "textposition": ["left", "left", "bottom", "bottom left", "top left", "top"],
       "error_y": {
         "array": [0.1, 0.2, 0.3, 0.1, 0.3, 0.2],
         "arrayminus": [0.1, 0.2, 0.1, 0.1, 0.1, 0.2]
@@ -32,23 +32,82 @@
       },
       "cliponaxis": false
 
+    },
+    {
+      "mode": "markers",
+      "x": [1, 1, 2, 3, 3, 2],
+      "y": [2, 1, 1, 1, 2, 2],
+      "marker": {
+        "size": [15, 20, 40, 25, 50, 40],
+        "opacity": 1
+      },
+      "cliponaxis": false,
+      "xaxis": "x2",
+      "yaxis": "y2"
+    },
+    {
+      "mode": "markers+text",
+      "x": [1, 1.5, 2.5, 3, 2.5, 1.5],
+      "y": [1.5, 1, 1, 1.5, 2, 2],
+      "marker": {
+        "size": 30
+      },
+      "text": "clipped<br>should not see this!",
+      "textposition": ["left", "bottom", "bottom", "right", "top", "top"],
+      "cliponaxis": true
     }
   ],
   "layout": {
     "xaxis": {
+      "domain": [0, 0.48],
       "range": [1, 3],
       "showline": true,
       "linewidth": 2,
-      "mirror": "all"
+      "mirror": "all",
+      "layer": "below traces"
     },
     "yaxis": {
       "range": [1, 2],
       "showline": true,
       "linewidth": 2,
-      "mirror": "all"
+      "mirror": "all",
+      "layer": "below traces"
+    },
+    "xaxis2": {
+      "anchor": "y2",
+      "range": [1, 3],
+      "domain": [0.52, 1],
+      "showline": true,
+      "linewidth": 2,
+      "mirror": "all",
+      "layer": "above traces"
+    },
+    "yaxis2": {
+      "anchor": "x2",
+      "range": [1, 2],
+      "showline": true,
+      "linewidth": 2,
+      "mirror": "all",
+      "side": "right",
+      "layer": "above traces"
     },
+    "annotations": [{
+      "showarrow": false,
+      "xref": "paper", "yref": "paper",
+      "x": 0.24, "y": 0.5,
+      "xanchor": "center",
+      "text": "axis layer<br>below traces"
+    }, {
+      "showarrow": false,
+      "xref": "paper", "yref": "paper",
+      "x": 0.74, "y": 0.5,
+      "xanchor": "center",
+      "text": "axis layer<br>above traces"
+    }],
     "showlegend": false,
     "dragmode": "pan",
-    "hovermode": "closest"
+    "hovermode": "closest",
+    "height": 500,
+    "width": 800
   }
 }