[Bugfix] Properly escape NFO files (#168)

* Properly escaped NFO file contents

* Added an NFO backfill worker

* Added a try-catch to the backfill since I _really_ don't want failures to halt app boot

lib/pinchflat/utils/xml_utils.ex

@@ -0,0 +1,17 @@
+defmodule Pinchflat.Utils.XmlUtils do
+  @moduledoc """
+  Utility methods for working with XML documents
+  """
+
+  @doc """
+  Escapes invalid XML characters in a string
+
+  Returns binary()
+  """
+  def safe(value) do
+    value
+    |> to_string()
+    |> Phoenix.HTML.html_escape()
+    |> Phoenix.HTML.safe_to_string()
+  end
+end