fix(data-loaders): avoid exporting data loaders in runtime

fix #663

BREAKING CHANGE: Data loader features must be imported from
`unplugin-vue-router/data-loaders`. They were accidentally exposed
through runtime but this was never documented. Your IDE might have added
auto imports automatically and removing this will avoid future issues.
You simply need to replace missing imports.

Author: posva

src/runtime.ts

@@ -1,11 +1,5 @@
 import type { RouteRecordRaw } from 'vue-router'
 
-// new data fetching
-export * from './data-loaders/entries/index'
-
-// NOTE: for tests only
-// export * from './data-loaders/defineQueryLoader'
-
 /**
  * Defines properties of the route for the current page component.
  *