GIP: New Geonetwork users/groups synchronization

[Florian Necas]

I want to open a new GIP with this PR https://github.com/georchestra/geonetwork/pull/350.

It introduces a new synchronization mechanism between console and geonetwork.

Intended purpose:

It aims to solve two problems in Geonetwork synchronization:

- Org based sync isn't granular enough to allow a user to be in multiple Geonetwork groups.

- Role based sync is not understable enough and we easily loose track of what is sync between georchestra's console and GN (and datahub)

Expected benefits for the community

This new sync, role_per_org, extends the behavior of org based sync but with new extra roles assignement.

This way we can keep actual behavior, but with creating a new role (PSC:GN_REVIEWER by example), we can add user as reviewer inside PSC group.

Combined to organization-level roles introduced in 25, I find it quite powerful and modular without bringing a lot of ocmplexity.

How it will be implemented

Like this : https://github.com/georchestra/geonetwork/pull/350

With some extra docs.

Potential risks, and ways to work around them

Need to extra check how it "self-handle" groups and metadatas rights when moving from role based sync to this one (or even good old org based sync).