Warn when there is an unused dependency

[bernardoduarte]

I've configured my fences.json on my project and tried to add a unused dependency to see if it would warn. I've added axios and, despite it not beign used in any of the files watched by this fences.json, it didn't warn me about missing dependency usage or unused dependency. I think it would be a great addition to this package as it would help us to better maintain our modules.

Here is my fences.json example:

{
  "tags": [ "main" ],
  "exports": [
      {
          "modules": "adapters/*"
      },
      {
          "modules": "factories/*"
      },
      {
          "modules": "module"
      }
  ],    
  "imports": [
      "domain",
      "data",
      "infra",
      "presentation"
  ],
  "dependencies": [
      "@nestjs/*",
      "express",
      "axios"
  ]
}