[IMP] web_editor: adding dirtyness check when in collab mode

This commit adds a new event listener on the odooEditor which listens for
external history steps (if collab mode is enabled), and changes the state of
the record's dirtyness when a user receives external steps.

This way a user will see that the record has been modified when he is editing
a collaborative html field.

task-3609594

closes odoo/odoo#145928

Related: odoo/enterprise#51579
Signed-off-by: Nicolas Bayet (nby) <nby@odoo.com>

addons/web_editor/static/src/js/backend/html_field.js

@@ -315,6 +315,12 @@ export class HtmlField extends Component {
             this.props.record.model.bus.trigger("FIELD_IS_DIRTY", this._isDirty())
         );
 
+        if (this.props.isCollaborative) {
+            this.wysiwyg.odooEditor.addEventListener("onExternalHistorySteps", () =>
+                this.props.record.model.bus.trigger("FIELD_IS_DIRTY", this._isDirty())
+            );
+        }
+
         this.isRendered = true;
     }
     /**