JSX not supported in config with CRA

Describe the bug As reported by @rlecaro2 and @Akaryatrh on #5183, JSX is not supported inside of the .storybook folder.

To Reproduce Steps to reproduce the behavior:

1. Install create-react-app
2. Install Storybook

Expected behavior JSX will be supported inside the .storybook folder.

System: All.

Additional context We had a similar issue with TypeScript which was resolved. It’s likely that this issue doesn’t occur when working with TypeScript, but this needs more investigation.

It’s been reported that [adding babel-loader to devDependencies fixes the issue[(https://github.com/storybookjs/storybook/issues/5183#issuecomment-505617245), this also needs investigation.

[jamesg1]

@jamesg1, would you mind sharing your tsconfig,json if possible? You can cut out anything confidential.

Yeah sure no problem:

{
  "compilerOptions": {
    "target": "es5",
    "lib": [
      "dom",
      "dom.iterable",
      "esnext"
    ],
    "allowJs": true,
    "skipLibCheck": true,
    "esModuleInterop": true,
    "allowSyntheticDefaultImports": true,
    "strict": true,
    "forceConsistentCasingInFileNames": true,
    "module": "esnext",
    "moduleResolution": "node",
    "resolveJsonModule": true,
    "isolatedModules": true,
    "noEmit": true,
    "jsx": "preserve",
    "baseUrl": "src",
    "rootDirs": [
      "src",
      "stories",
      ".storybook"
    ]
  },
  "include": [
    "src",
    ".storybook"
  ],
  "exclude": [
    "src/**/*.js"
  ]
}

[shilman]

@mrmckeb I like the first solution also 💯 Thanks for being on top of this! If there’s enough pushback we can also special-case include the /stories folder in addition to the /.storybook folder, but let’s try the more restrictive version first and see if it’s good enough.