feat: use @babel/runtime helpers and define module field in package.json

[rafaeltavares]

Hi, I would like to propose some quality of life changes to this package.
This will require a major version bump.

1. Update @babel/* and remove unused dependencies.
2. Use external helpers via @babel/runtime and @babel/plugin-transform-runtime.
   This change removes the need of a global regenerator-runtime declaration and reduce bundle sizes since babel helpers are not being inlined on every file. See https://babeljs.io/docs/en/babel-plugin-transform-runtime
3. Unify browser support for CJS and ES modules via @babel/preset-env.
4. Declare module field on package.json so module bundlers can resolve ES imports.
5. Create separate bundle for IE11: react-relay-network-modern/ie11
6. Drop support for other dead browsers.

browsers without official support or updates for 24 months. Right now it is IE 11, IE_Mob 11, BlackBerry 10, BlackBerry 7, Samsung 4, OperaMobile 12.1 and all versions of Baidu.
https://github.com/browserslist/browserslist#full-list