Migrate to yarn v4

Use yarn PnP which forces us to install some more explicit dependencies.

Change-Id: Ib35c5c71a37081c98778937bde5a23bf997dd54c

.vscode/extensions.json

@@ -0,0 +1,7 @@
+{
+  "recommendations": [
+    "arcanis.vscode-zipfs",
+    "dbaeumer.vscode-eslint",
+    "esbenp.prettier-vscode"
+  ]
+}

.vscode/settings.json

@@ -0,0 +1,10 @@
+{
+  "search.exclude": {
+    "**/.yarn": true,
+    "**/.pnp.*": true
+  },
+  "eslint.nodePath": ".yarn/sdks",
+  "prettier.prettierPath": ".yarn/sdks/prettier/index.cjs",
+  "typescript.tsdk": ".yarn/sdks/typescript/lib",
+  "typescript.enablePromptUseWorkspaceTsdk": true
+}