Static keys for facet options (GSI-333)

[TheByronHimes]

Previously, facets returned by queries took the format:

"facets": [
      {
        "key": "alias",
        "name": "Alias",
        "options": {
          "DS_3": 1,
          ...
        }
      }
    ]

but to aid frontend's usage of the data, it will be restructured with this PR to look like this:

"facets": [
      {
        "key": "alias",
        "name": "Alias",
        "options": [
          {"value": "DS_3", "count": 1},
          ...
        ]
      }
    ]

[ac-jorellanaf]

Looks good.

[mephenor]

I don't fully get everything that's happening, but I think I understand enough to approve this