Open api endpoint /api/1/provenance/ to read a content's provenance information

This must answer the question, where did you see the content identified by a given hash (hash being sha1, sha1_git, sha256. The expected answer is of the form: "content appeared in revision which we have seen in visit of origin with path "

This replaces the old route /api/1/browse/algo_hash:content_hash. (deactivated in c2a466e6).

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Migrated from T553 (view on Phabricator)