Update recommended extension for Lit

Bug: none
Change-Id: Iff4c8a320d8f0344fc56a86f32ca796fb41e078b
Reviewed-on: https://chromium-review.googlesource.com/c/devtools/devtools-frontend/+/5953721
Commit-Queue: Benedikt Meurer <[email protected]>
Commit-Queue: Nikolay Vitkov <[email protected]>
Auto-Submit: Nikolay Vitkov <[email protected]>
Reviewed-by: Benedikt Meurer <[email protected]>

Author: Lightning00Blade

.vscode/extensions.json

@@ -1,7 +1,7 @@
 {
   "recommendations": [
-      "dbaeumer.vscode-eslint",
-      "bierner.lit-html",
-      "npclaudiu.vscode-gn"
+    "dbaeumer.vscode-eslint",
+    "runem.lit-plugin",
+    "npclaudiu.vscode-gn"
   ]
-}
+}