Support npm workspaces

[mikavilpas]

I have an npm project that uses npm workspaces:

# workspace root contains the package file and the lock file
/package.json
/package-lock.json

# a workspace ("package") contains the package file only
/packages/my-package/package.json

Currently if I open my workspace root /, I see npm-gui shows the packages that are installed at the root level. This is as expected.

If I open my workspace at /packages/my-package, it shows the packages that are installed in that workspace, but the installed versions are reported as "missing".

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To properly support workspaces, I think these things would be good:

• when viewing /, provide a way to navigate to the workspaces (via a link)
• similarly, when viewing /packages/my-workspace, provide a way to navigate back to the package root
• correctly show the installed versions for workspace packages (they are listed in the root package-lock.json)