fix: ensure vue init works when installed with npm

Author: yyx990803

packages/@vue/cli-init/index.js

@@ -1 +1,8 @@
-require('vue-cli/bin/vue-init')
+const execa = require('execa')
+const binPath = require.resolve('vue-cli/bin/vue-init')
+
+execa(
+  binPath,
+  process.argv.slice(process.argv.indexOf('init') + 1),
+  { stdio: 'inherit' }
+)

packages/@vue/cli-init/package.json

@@ -21,6 +21,7 @@
   },
   "homepage": "https://github.com/vuejs/vue-cli/packages/@vue/cli-init#readme",
   "dependencies": {
+    "execa": "^0.9.0",
     "vue-cli": "^2.9.2"
   }
 }