This commit moves `GargConfig` and the other config-related
data structures back into gargantext, so that they can be edited
and expanded without needing to worry about the prelude project.

Using goldenVsStringDiff creates problems with CI trying to locale
`gargantext-cli -- golden-file-diff`.

This commit extends the reverse proxy for the microservices so that it
would serve a custom `/config` file which would contain the correct
baseUrl to initialise the websocket connection correctly.

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.