Deprecate additional positional args to plot_{surface,wireframe}.

Previously, a 4th positional parameter to plot_surface would be
nonsensically interpreted as the `sizes` property of the PolyCollection,
and a 4th positional parameter would be interpreted as the `linewidths`
of the LineCollection, which is more useful but not so obvious.

Instead, deprecate these uses (one can still set these using keyword
arguments), in preparation of overloading these functions as
`plot_{surface,wireframe}([X, Y], Z)` instead (i.e., defaulting X and Y
to the correct meshgrid, similarly to what we already do e.g. for
the 2D `pcolor`-style functions).

Author: anntzer

doc/api/next_api_changes/deprecations/19176-AL.rst

@@ -0,0 +1,5 @@
+Extra positional parameters to ``plot_surface`` and ``plot_wireframe``
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+Positional parameters to `~.axes3d.Axes3D.plot_surface` and
+`~.axes3d.Axes3D.plot_wireframe` other than ``X``, ``Y``, and ``Z`` are
+deprecated.  Pass additional artist properties as keyword arguments instead.

lib/mpl_toolkits/mplot3d/axes3d.py

@@ -1493,6 +1493,7 @@ def plot(self, xs, ys, *args, zdir='z', **kwargs):
 
     plot3D = plot
 
+    @_api.delete_parameter("3.4", "args", alternative="kwargs")
     def plot_surface(self, X, Y, Z, *args, norm=None, vmin=None,
                      vmax=None, lightsource=None, **kwargs):
         """
@@ -1764,6 +1765,7 @@ def norm(x):
 
         return colors
 
+    @_api.delete_parameter("3.4", "args", alternative="kwargs")
     def plot_wireframe(self, X, Y, Z, *args, **kwargs):
         """
         Plot a 3D wireframe.