Still needs to fix some hardcoded URLs. The problem with websockets is
that they use the first URL fragment to determine the documentId,
therefore we cannot proxy to `http://localhost:8009/notes/<frameId>`
because the underlying WS connection will use `noteId=notes`, which is
wrong.

This beefy commit removes the old (unnamed) Servant API.

This big commit ties the knot with the named _routes_ by providing
concrete server (i.e. handlers) implementations.

Merge branch '345-docs-tsv-export-import-check-and-maintain-consistency-between-export-and-import-formats' of https://gitlab.iscpif.fr/gargantext/haskell-gargantext into 345-docs-tsv-export-import-check-and-maintain-consistency-between-export-and-import-formats