Move threads e2e tests over to cypress (#8501)

* Add non-consent (default) Synapse template

* Add consent test

* Add create room test

* Stash work

* Initial threads tests

* fix

* Delete old threads e2e tests, plan new ones

* Fix typed s'more

* Try something else

* specify d.ts

* Fix types once and for all?

* Fix the consent tests

* Iterate threads test harness

* Fix dispatcher types

* Iterate threads test

* fix typing

* Alternative import attempt

* let it break let it break let it break

* Tweak types

* Stash

* delint and update docs

* null-guard scrollIntoView

* Iterate threads test

* Apply suggestions from code review

cypress.json

@@ -1,5 +1,7 @@
 {
     "baseUrl": "http://localhost:8080",
     "videoUploadOnPasses": false,
-    "projectId": "ppvnzg"
+    "projectId": "ppvnzg",
+    "experimentalSessionAndOrigin": true,
+    "experimentalInteractiveRunEvents": true
 }