npm workspaces detection should not find the same workspace twice

[targos]

When npm workspaces are used, npm creates for each workspace a symbolic link under node_modules that points to the module in the workspace. The problem is that this extension finds it and then proposes two options when you try for example to list routes:

If there are no use cases for looking inside node_modules, these folders can just be ignored. Otherwise, it may be possible to use fs.realpath to make sure the same absolute path isn't listed twice.