This diff is the first step towards implementing the search query language which can be directly translated
to Elasticsearch (or any other search backend) queries and is also useful for the introducing
autocomplete in the swh archive.
Also, we need a parser that can be used in the swh.search backend as well as the swh.web interface so
we've decided to go with TreeSitter which satisfies these conditions, is easier to write (written in JS),
and is compatible with many languages.