Subdirectories are not watched in dev environment for Linux OS

[Rahmon]

Describe the bug
The recursive option in fs.watch is only supported on macOS and Windows. So on Linux the subdirectories aren't watched when i run npm run dev.

gutenberg/bin/packages/watch.js

Line 36 in 84e1e80

fs.watch( path.resolve( p, 'src' ), { recursive: true }, ( event, filename ) => {

To Reproduce
Steps to reproduce the behavior:

1. On Linux OS clone the project.
2. Run npm i and npm run dev.
3. Make some change in file: packages/block-library/src/paragraph/index.js
4. Change isn't watched (nothing happens)

Expected behavior
"watch" to work on Linux too.. 😞 .

Possible solution
I've used node-watch package.

Desktop (please complete the following information):

• OS: Fedora 29
• Version 4.7.1

[gziolo]

It was fixed in #13448.