Improve e2es (retries, wasm, server-actions, etc...) (#636)

* add vitest.config.ts file with retry for better tests stability

* add new e2e features to test wasm

* avoid inconsistent kebab-case

* use latest wrangler release

notes:
 - this is needed so that we can add e2e tests for server actions: cloudflare/workers-sdk#4630
 - we the commit also updates node from 18 to 20 in e2e github acitons testing, this is necessary for using the latest
wrangler release, see: cloudflare/workers-sdk#4563 (comment)

* add app server-actions e2e test

* remove unnecessary existsSync assertion in processVercelOutput unit tests

.github/actions/node-setup/action.yaml

@@ -8,10 +8,10 @@ inputs:
 runs:
   using: composite
   steps:
-    - name: Setup Node.js 18.x
+    - name: Setup Node.js 20.x
       uses: actions/setup-node@v3
       with:
-        node-version: 18.x
+        node-version: 20.x
 
     - name: Get current node version
       id: node-version