Implement API endpoint for /collections/[collection]

[neuromusic]

Given a collection slug (e.g. alfa-cohort, bravo_cohort) or full URL (e.g. https://raw.githubusercontent.com/chanzuckerberg/napari-hub-collections/main/collections/alfa-cohort.yml), implement an API endpoint that returns metadata for that collection in this format (pulled from the collections tech spec)

{
  "title": "Alfa Cohort",
  "updated_date": "2022-04-29",
  "summary": "Plugins created by participants in the the napari Alfa Cohort",
  "description": "Plugins created by participants in the the napari Alfa Cohort. Lorem ipsum dolor sit amet, consectetur adipiscing elit.  Vestibulum faucibus elit at erat volutpat, id consequat felis egestas. Vestibulum id eleifend purus.  Cras tortor felis, congue in pulvinar nec.\n",
  "cover_image": "national-cancer-institute-evhLgfOjU5Y-unsplash.jpg",
  "plugins": [
    {
      "name": "napari-yapic-prediction",
      "comment": "Classify every pixel from your own pre-trained deep learning models"
    },
    {
      "name": "cellfinder-napari",
      "comment": "Quickly detect neurons in whole brain flourescent imaging data"
    },
    {
      "name": "napari-cellpose",
      "comment": "Segment cells and nuclei leveraging cytoplasm channels"
    },
    {
      "name": "napari-nucleaizer",
      "comment": "Segment cellular nuclei across a wide range of imaging modalities"
    },
    {
      "name": "stardist-napari",
      "comment": "Segment nuclei from fluorescent and histopathology images"
    }
  ],
  "curator": {
    "name": "Justin Kiggins",
    "title": "Product Manager",
    "affiliation": {
      "institution": "Chan Zuckerberg Initiative",
      "website": "https://chanzuckerberg.com"
    },
    "links": {
      "orcid": "0000-0002-4638-7015",
      "twitter": "https://twitter.com/neuromusic",
      "github": "https://github.com/neuromusic",
      "website": "https://justinkiggins.com"
    }
  }
}

Notes

• We are fetching this data from the collections repo, https://github.com/chanzuckerberg/napari-hub-collections
• See https://gist.github.com/richaagarwal/3601107b634c9e867dd689dd0d7183cf for example calls to get this data
• While the cover image values above are just the filenames, @codemonkey800 has requested that they are the full path, e.g. https://raw.githubusercontent.com/chanzuckerberg/napari-hub-collections/main/images/national-cancer-institute-4zA4w-dr5WM-unsplash.jpg
• If we decide we need caching (via potentially CloudFront), it will be handled in a follow-up ticket.