Use the local context when launching a graph_open action

Using the local context allow us to access the context of the field shown by
the graph when the graph shows a One2Many field.

Closes #14341
(grafted from f186b83936dbde32aca06b3a329bf519df2c8232)

--HG--
branch : 6.0

sao/src/view/graph.js

@@ -245,7 +245,7 @@
         },
         action: function(data, element) {
             var ids = this.ids[this._action_key(data)];
-            var ctx = jQuery.extend({}, this.view.screen.group._context);
+            var ctx = jQuery.extend({}, this.view.screen.group.local_context);
             delete ctx.active_ids;
             delete ctx.active_id;
             Sao.Action.exec_keyword('graph_open', {

tryton/tryton/gui/window/view_form/view/graph_gtk/graph.py

@@ -138,7 +138,7 @@ class Graph(Gtk.DrawingArea):
     def action_keyword(self, ids):
         if not ids:
             return
-        ctx = self.group._context.copy()
+        ctx = self.group.local_context.copy()
         if 'active_ids' in ctx:
             del ctx['active_ids']
         if 'active_id' in ctx: