This fixes commit 5d5300cd which
automatically changed all 'return' to 'pure' in our code, resulting in
broken SQL etc.

The issue was that when search was performed, the initial table didn't
have an archive ready and so first commit resulted in some errors on
the frontend. This fix performs the commit after flow is finished.

We now require CoreNLP listening on port :9000. We will have to find
a way to spin that up in CI as well.

This commit refactors the codebase to add a new function called
`addDocumentsToHyperCorpus` which generalises the common pattern of
calling `insertMasterDocs` and later adding the documents via the DB
`Doc` functions.

It also "lowers" some functions to run into a plain `DBCmd`.

Fixes #258

This commit fixes the issue of the "empty Ngrams". The culprit was a bug
in the `arxiv-api` package, which was fixed by:

gargantext/crawlers/arxiv-api!2 (commits)

In a nutshell, due to the fact the relevant `Conduit` was never
completing, it was blocking the `flow` function, which was endlessly
waiting for the last part of the results to arrive.

Hence we were never calling the `flowCorpusUser`, which is the function
responsible for generating the Ngrams.

This important commit introduces the 'DbCmd' constraint set, allowing DB
functions to require only a connection pool and some `GargConfig`.

This is to prevent accidental updates of hyperdata with other JSON
structs.

The bug was introduced in

gargantext/haskell-gargantext!177 (diffs)

It caused hyperdata to be updated with whole corpus, serialized, hence
hyperdata inside hyperdata.

This reverts merge request !166

This reverts commit b3fb1a16

It introduced changes which cause issues described in
gargantext/purescript-gargantext#571

This reverts commit a444cb30.

This reverts commit 22b14f56.

This reverts commit d04cf03b, reversing
changes made to e213a4bf.