Tests: Add basic e2e tests for frontend plugin sandbox (#70759)

* Add initial e2e tests for sandboxing

* Add tests for sandbox on

* Add additional sandbox tests

* Move sandbox into various suite

* Test drone setup

* Move variable

* Update drone

* Update plugins path for e2e

* Revert drone changes

* use drone from main

* Use lib.star from main

* Move sandbox test to its own suite

* Expand methods to inject iframes

* Restore e2e script

* Add back change to script

* Update tests for trusted types

* Integrate custom plugins into grafana-server

* Echo for deubging

* add debugging message

* Expand message

* Add extra for ci

* fix path

* Improve start-server logic

* Remove duplicated logic

* Restore file deleted by mistake

* Restore file to main
p

* restore file

* Restore start script

* Update e2e/panels-suite/frontend-sandbox-panel.spec.ts

Co-authored-by: Levente Balogh <balogh.levente.hu@gmail.com>

---------

Co-authored-by: Levente Balogh <balogh.levente.hu@gmail.com>

e2e/custom-plugins/frontend-sandbox-panel-test/plugin.json

@@ -0,0 +1,25 @@
+{
+  "$schema": "https://raw.githubusercontent.com/grafana/grafana/master/docs/sources/developers/plugins/plugin.schema.json",
+  "type": "panel",
+  "name": "Sandbox test plugin",
+  "id": "sandbox-test-panel",
+  "info": {
+    "keywords": ["panel"],
+    "description": "",
+    "author": {
+      "name": "Grafana"
+    },
+    "logos": {
+      "small": "img/logo.svg",
+      "large": "img/logo.svg"
+    },
+    "links": [],
+    "screenshots": [],
+    "version": "1.0.0",
+    "updated": "2023-06-27"
+  },
+  "dependencies": {
+    "grafanaDependency": ">=10.0",
+    "plugins": []
+  }
+}