[FIX] web: propagate context for pivot view fields

On the "+" in the pivot views to group by given fields, these field were
not translated in the user choosen language.

closes #8656
opw-649918

addons/web/static/src/js/view_pivot.js

@@ -63,7 +63,7 @@ instance.web.PivotView = instance.web.View.extend({
         var self = this;
         this.$table_container = this.$('.o-pivot-table');
 
-        var load_fields = this.model.call('fields_get', [])
+        var load_fields = this.model.call('fields_get', [], {context: this.dataset.get_context()})
                 .then(this.prepare_fields.bind(this));
 
         return $.when(this._super(), load_fields).then(this.render_buttons.bind(this)).then(function(){