CLI/Vue 2: install vue-loader upon init of vue 2 storybook

[phated]

Issue: #14011

What I did

I'm not sure if we should do this or not.

Essentially, the @storybook/vue package has a peerDep on vue-loader and errors if someone doesn't install it (as was noted in the linked issue). It seems that some versions of the Vue CLI don't use webpack and don't install this dependency, so we could specify this as an extraPackages so it is always installed by sb init. Thoughts?

How to test

• Is this testable with Jest or Chromatic screenshots? ❌
• Does this need a new example in the kitchen sink apps? ❌
• Does this need an update to the documentation? ❌

If your answer is yes to any of these, please make sure to include it in your PR.

[shilman]

Makes sense to me. Thanks for grabbing this! 🙏

[shilman]

Hmm, then again by that logic why not install all the peer deps? Where to draw the line? 🤔

  "peerDependencies": {
    "@babel/core": "*",
    "babel-loader": "^7.0.0 || ^8.0.0",
    "css-loader": "*",
    "ts-loader": "^6.2.2",
    "vue": "^2.6.8",
    "vue-loader": "^15.7.0",
    "vue-template-compiler": "^2.6.8"
  },

[pocka]

Looks good to me but I couldn't find

It seems that some versions of the Vue CLI don't use webpack and don't install this dependency,

the changes or issues in https://github.com/vuejs/vue-cli...

[phated]

Hmm, then again by that logic why not install all the peer deps? Where to draw the line?

I don't have an answer for this, that's why I didn't know if we should do it. For Vue 3, I added the loader because you have to have v16 which is tagged @next on npm. It was the only extra dependency that I needed to layer onto a fresh "Vue CLI"-created project to get it to run.