The previous behaviour assumed that in a bundled package path,
there is always `node_modules` directory on each other spot – i.e.:
npm/node_modules/<dep1>/node_modules/<subdep>
^ ^
With namespaced bundled packages, this is no longer necessary the truth:
npm/node_modules/@nmcli/<dep1>/node_modules/…
^ ! – expected node_modules
---
The previous implementation considered any directory not named
`node_modules` as a package directory, and tried to process it as such.
Among other things, it pruned the list of subdirectories to be processed
to just another `node_modules` subdir, if that existed.
With namespaced packages, this pruning in essence happened too soon,
and so they were skipped altogether.
With this patch applied, only directories that directly contain
the `package.json` file are processed as package directories,
meaning that the walk should correctly descend into namespaces
(even nested ones, if they appear).
Resolves: rhbz#2029904
