This commit splits the /export (renaming it to just remote) and tuck it
under the /node hierarchy. The import also lives tucked in the /node.

* Rename `exampleS` into `exampleSchema`;
* Revert commit about the public keys & co;

This reverts commit 3ea32b50.

Exporting a corpus works, as it also exports its children, but for
example the docs and terms nodes do not have any associated content.
This is because those are stored in separate DB tables, and we need
to find a way to export those as well.

It typechecks but it exchange only a very simple string and
it prints it.

This adds a new randomly-generated pair of (PublicKey, PrivateKey) to be
later used to send messages between instances.

It also:

* Returns a remote transfer pub key inside an AuthResponse
* Adds pubKey roundtrip test

[graphql] fix droping field prefixes

See merge request !379

Upgrade 'haskell-bee' version, also bump up versions of some packages

See merge request !377

Resolve "Fix test build warnings"

See merge request !376

Also, add -Werror to tests so that no warnings in tests are reported anymore.

Switch to OpenAPI3 from Swagger2, to use proper Bearer token

Closes #427

See merge request !369