ole: add icon_width/height to .add_ole_object()

The caller will need to specify the icon height and width when providing
their own custom icon image. Add optional parameters to
`.add_ole_object()` suitable for that purpose and update the
documentation.

Author: scanny

pptx/shapes/shapetree.py

@@ -279,7 +279,16 @@ def add_group_shape(self, shapes=[]):
         return self._shape_factory(grpSp)
 
     def add_ole_object(
-        self, object_file, prog_id, left, top, width=None, height=None, icon_file=None
+        self,
+        object_file,
+        prog_id,
+        left,
+        top,
+        width=None,
+        height=None,
+        icon_file=None,
+        icon_width=None,
+        icon_height=None,
     ):
         """Return newly-created GraphicFrame shape embedding `object_file`.
 
@@ -289,8 +298,9 @@ def add_ole_object(
         which case the default icon size is used. This is advised for best appearance
         where applicable because it avoids an icon with a "stretched" appearance.
 
-        `object_file` may either be a str path to the file or a file-like
-        object (such as `io.BytesIO`) containing the bytes of the object file.
+        `object_file` may either be a str path to a file or file-like object (such as
+        `io.BytesIO`) containing the bytes of the object to be embedded (such as an
+        Excel file).
 
         `prog_id` can be either a member of `pptx.enum.shapes.PROG_ID` or a str value
         like `"Adobe.Exchange.7"` determined by inspecting the XML generated by
@@ -302,6 +312,13 @@ def add_ole_object(
         operating-system limitations). The image file can be any supported image file.
         Those produced by PowerPoint itself are generally EMF and can be harvested from
         a PPTX package that embeds such an object. PNG and JPG also work fine.
+
+        `icon_width` and `icon_height` are `Length` values (e.g. Emu() or Inches()) that
+        describe the size of the icon image within the shape. These should be omitted
+        unless a custom `icon_file` is provided. The dimensions must be discovered by
+        inspecting the XML. Automatic resizing of the OLE-object shape can occur when
+        the icon is double-clicked if these values are not as set by PowerPoint. This
+        behavior may only manifest in the Windows version of PowerPoint.
         """
         graphicFrame = _OleObjectElementCreator.graphicFrame(
             self,