Add filtering to the `/titles` listing endpoint

refer https://github.com/openzim/cms/issues/29#issuecomment-987848283

GET /titles:

{
  "meta": {
    "count": 2,
    "limit": 10,
    "skip": 0
  },
  "items": [
    {"ident": "wikipedia_fr_all_maxi"},
    {"ident": "wikipedia_fr_all_nopic"}
  ]
}

Rule of thumb is that all list endpoints should use the same wrapping schema with the meta info for pagination. It means that it should also accept skip and limit parameters to control the result list. This is similar to what the zimfarm API does.

Now, this endpoint is gonna be the most used and must be versatile so it serves most if not all of the UI's needs (as well as other needs). It thus needs to allow filtering and payload-control using GET parameters.

Filters:

?lang=fra,eng to filter results based on ISO-639-3 lang codes (intersection)
?lang=fra|eng to filter results based on ISO-639-3 lang codes (union)
?metadata-name=wikipedia_fr_test to filter based on a meta (Name here). Value can include the * character (ex: wikipedia_*_maxi, *_nopic, etc). Illustration_* are not supported obviously.
?tag=wikipedia,kids, ?tag=wikipedia|wikibooks to filter results based on Tag (intersection and union) with support for exclusion: tag=wikipedia,!fun|ted,kids (matches Titles with wikipedia or ted that also have the kids tag and not the fun tag) !wikipedia would match all but the wikipedia ones.

Payload-control:

?with_metadata=title,scraper,illustration_48x48: includes the requested metadata in response. all is a shortcut for including all metadata (including illustration). all_text is same but only text-ones. illustration is an alias for illustration_48x48.
?with_tags: include tags (all) into response.
?with_languages: include languages into response.

Complete complex request: GET /titles?lang=fra&metadata-scraper=*1.11&tag=!wikipedia&with_tags&with_languages&with_medata=all

[
  {
    "ident": "wikihow_fr_all_maxi",
    "languages": [
      "fra"
    ],
    "metadata": {
      "Creator": "Wikipedia",
      "Description": "offline version of Wikipedia in Ganda",
      "Flavour": "maxi",
      "Language": "fra",
      "Name": "wikipedia_fr_all_maxi",
      "Publisher": "Kiwix",
      "Tags": "wikihow;_category:wikipedia",
      "Title": "Wikipedia",
      "Scraper": "wikihow2zim 1.11",
      "Illustration_48x48": "xxx"
    },
    "tags": [
      "wikihow",
      "_category:wikipedia"
    ]
  }
]

openzim / cms

Add filtering to the `/titles` listing endpoint #41