fix(plugin-vue): support vapor template-only component (#529)

Author: edison1105

Diff for: packages/plugin-vue/src/main.ts

@@ -345,7 +345,9 @@ async function genScriptCode(
   code: string
   map: RawSourceMap | undefined
 }> {
-  let scriptCode = `const ${scriptIdentifier} = {}`
+  // @ts-expect-error TODO remove when 3.6 is out
+  const vaporFlag = descriptor.vapor ? '__vapor: true' : ''
+  let scriptCode = `const ${scriptIdentifier} = { ${vaporFlag} }`
   let map: RawSourceMap | undefined
 
   const script = resolveScript(descriptor, options, ssr, customElement)