Allow each Component to be imported from respective root folder: multi-entry support

[andreawyss]

Sorry for the question, but I could not find info in the docs on how to do this.

I have a library of React Components with a source structure similar to:
https://github.com/mui-org/material-ui/tree/master/packages/material-ui/src

Is it possible to setup TSDX to build the library so that one can import individual components from their individual root folders?

   import Avatar from 'my-library/Avatar';
   import Button from 'my-library/Button';

Currently using TSDX we are forced to import all the components from the root index

   import { Avatar, Button } from 'my-library';

Thank you.

[ambroseus]

@andreawyss you are not alone)
#175 (comment)

[ambroseus]

material-ui has additional post-build step to create sub-modules/packages for each child folder
https://github.com/mui-org/material-ui/blob/2a872f81d0c1b1dee8cc7bed169a2e89d36adaad/packages/material-ui/package.json#L33
https://github.com/mui-org/material-ui/blob/master/scripts/copy-files.js

[agilgur5]

Related to or duplicate of #365, #367, #175 , #276 , #299, #321