Tiptap RTE: Block selection (#19811)

* Removed `cursor: not-allowed` style

* Sets the `umb-rte-block` `user-select` to `all`

* Adds an "invisible" selection background to `umb-ref-rte-block`

* Sets the `umb-ufm-render` text-content to be visible

* Adds `aria-hidden` attribute

* Bumped version of test helper

* Fixed the failing tests due to UI changes

* Adds `pointer-events: none` to selection-background

---------

Co-authored-by: Nhu Dinh <hnd@umbraco.dk>

tests/Umbraco.Tests.AcceptanceTest/package.json

@@ -21,7 +21,7 @@
   },
   "dependencies": {
     "@umbraco/json-models-builders": "^2.0.37",
-    "@umbraco/playwright-testhelpers": "^16.0.29",
+    "@umbraco/playwright-testhelpers": "^16.0.32",
     "camelize": "^1.0.0",
     "dotenv": "^16.3.1",
     "node-fetch": "^2.6.7"