QuadSinkFiles > iriToPath should prioritize longer prefixes

[pchampin]

Consider the following:

{
  "quadSink": {
    "@type": "QuadSinkFile",
    "log": true,
    "outputFormat": "application/n-quads",
    "fileExtension": "$.nq",
    "iriToPath": {
      "http://example.org/base/": "output/base/",
      "http://example.org/": "output/other/"
    }
  }
}

everything will end up in output/other, including the IRIs starting with "http://example.org/base/".

When several prefixes apply, I would expect the longer (most specific) to apply.