Previous to this commit, `get_user_root_node_folder` would fail with
a `UserHasTooManyRoots` in case this was called on a tree which had
more than one "public" folder.

We fix this by taking the oldest available node, which will always
correspond to the notion of "root", being the first ever created.

Also added a warning in `.ghci` in the form of a comment discouraging
people from overriding local REPL configuration options

This commit splits the policy checks we do on node operations into
"read" checks and "write" checks, so that we can enforce different kind
of policies based on the state of a node (i.e. published or not).

This commit refactors the `NodeNodeCategory` so that we create a better
hierarchy to account for node publication, including all the policies it
might have.

It also:

* Removes UserNodePublic from typesWhiteList in isNodeReadOnly

This commit refactors a bit the internal of the
`Gargantext.Database.Query.Tree` module so that it removes a lot of
repetitive boilerplate and paves the way to more interesting features.

It also:

* Adds the `isUserNode` boolean query
* Adjust source and target in publishNode and unpublishNode
* Pass the currently-logged-in user to tree API functions

It also:

* Amends tests for policy checks status code changes
* Fix a bug in isNodeReadOnly
* Adds a function to return all the nodes ids for the published
  nodes. Next we need to modify `findShared` & co to make sure that
  published notes will show somewhere in the users' tree.

Now this query accounts correctly for recursive children.

It also:

* Adds basic publish/unpublish works
* Add Move API tests scaffolding

Now a `NodeNodePoly` stores a typed `NodeNodeCategory`, we can use
to enforce invariants and making lookups more efficient.

This commit makes this function private to the `Table.NodeNode` module
as it's fairly low-level, and it doesn't let us embed logic to ensure we
are creating a valid node2node relationship. Better use one of the other
specialised functions.

This commit removes the `InsertDB` typeclass, an indirection which
wasn't very useful as it was being used in exactly one place in the
whole codebase (i.e. the share code).

Talking about share, this commit refactors things ever so slightly so
that we have a dedicated `shareNode` operation rather than using the
low-level `insertNodeNode`.

This commit splits the old `NodeAPIEndpoint` type into three;

* `NodeAPIEndpoint`, which will also contain the freeze endpoint;
* `AnnuaireAPIEndpoint`, which is the plain old node API without extra
  features;
* `CorpusAPIEndpoint`, which will also contain the publishin endpoint.

This split ensures that we don't add endpoints which do not belong to
all three categories, like before.

Furthermore this adds a public nodes SQL queries.
It also adds tests for getUserRootPublicNode

The previous commit did not work, because GHCi executed the contents of
`.ghci` *before* loading the project.
This commit makes a new command, `:ggload`, available from GHCi when in
the Gargantext project: typing `:ggload` will make available all symbols
from modules named `Prelude` in the Gargantext project.
The name `:ggload` as well as the set of modules to import are still
open to discussion.

As per issue #422, this commit makes it so that some modules are
automatically imported when entering the REPL.
The modules are every module named `Prelude`, but exactly which modules
should be imported is probably a discussion worth having.

This allows us to collect a /history/ of computing times.

The tracking is not perfect yet, as it keeps storing only the latest
available compute time. Also, there seems to be some precision loss
between that is reported by `timeMeasured` and what gets stored in the
DB.

This was because WS connection wasn't closed properly.