DashboardScene: Support for discard, start at transform back to save model and save drawer (#73873)

* SceneDashboard: Discard changes now works

* To save model works and start at save drawer

* Update

* Added missing file

* Refactorings to keep responsibility more logical

* Refactorings

* Removed file

* Fixed state issue

* Update

* Update

package.json

@@ -245,7 +245,7 @@
     "@grafana/lezer-traceql": "0.0.4",
     "@grafana/monaco-logql": "^0.0.7",
     "@grafana/runtime": "workspace:*",
-    "@grafana/scenes": "^0.25.0",
+    "@grafana/scenes": "^0.26.0",
     "@grafana/schema": "workspace:*",
     "@grafana/ui": "workspace:*",
     "@kusto/monaco-kusto": "^7.4.0",