feat: apply recommended file notice to feed_info

[KClough]

Summary:

Resolves #877

Adds a new annotation for recommended files and applies this annotation to feed_info.txt and shapes.txt.

Expected behavior:

A new validator warning is generated when either feed_info.txt is missing

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Here is the sample output from the validator for a data set with missing feed_info.txt:

{
  "notices": [
    {
      "code": "missing_recommended_file",
      "severity": "WARNING",
      "totalNotices": 1,
      "sampleNotices": [
        {
          "filename": "feed_info.txt"
        }
      ]
    }
]}

[maximearmstrong]

Perfect, LGTM! We can merge this one when #1151 is. Thanks @KClough