Revert "chore: Extract sidebar item injection token into separate package"

This reverts commit 8ac66380ad.

packages/cluster-sidebar/.eslintrc.js

@@ -1,6 +0,0 @@
-module.exports = {
-    extends: "@k8slens/eslint-config/eslint",
-    parserOptions: {
-      project: "./tsconfig.json",
-    },
-  };