feat: generate helper file for IntelliJ IDEA based IDEs

[superbiche]

This is a workaround for the issue https://github.com/antfu/unplugin-vue-components/issues/135 The nuxt-storm module is really nice but it works only with Nuxt.

This PR adds an option to generate the .components.gen.js file - basically what nuxt-storm does.

Works for both Vue 2 and Vue 3 (using a dirty workaround until https://youtrack.jetbrains.com/issue/WEB-48239 is fixed).

The current state is quite raw, I wanted to see if it worked first, and it does. There's still some types to check and probably write some tests, but I wanted to know first if you would agree to adding this feature.

Let met know if what you think, and by the way thanks for this plugin and the others.