Expose the authenticated_userid in an endpoint

[Natim]

Clients need to know what's their userid is, in order to set and manage permission.

We should expose that in either an extra endpoint or the root one.
We may use the same endpoint as #318 in case we decide to create one.

[Natim]

Also now that the creator have got an automatic write access it is a bit less urgent.

[Natim]

I propose to add a userid field in the home page so that we can fetch the userid when fetching the settings.

[Natim]

r? @n1k0 @leplatrem

[leplatrem]

I remember that @ametaireau did not agree with that, since the hello endpoint does not require authentication...
On my side, I don't have any strong opinion on this, and would r+ (with documentation and changelog updated)

[Natim]

Note that with this PR the hello endpoint doesn't require authentication. It is just that if you need a userid you will provide a user Authentication.

[Natim]

I will merge for now and ask @ametaireau when he comes back and we can change the behaviour before the next release if necessary.

The reason why I think this is a good and acceptable solution:

• We can retrieve the userid on the / endpoint as well as the settings (could be done in one request)
• We don't force people to access the / endpoint with an Authorization header

[n1k0]

Lagguy r+

[leplatrem]

I don't understand why we were in a hurry for this...

[Natim]

We are not.