LPS-32530 Implicit members lose their organization roles and teams removing their site membership

Hi @epgarcia, @JorgeFerrer,

Three commits for this pull request:
1. The minimal changes in the UI to avoid that the implicit users lose their organization roles and teams [@JorgeFerrer is agreed with this]
2. Changes in the service layer to:
- Avoid removing roles and teams for implicit users who are not going to be unset
- Avoid removing organization roles for sites

[I think we should clarify the concepts Group, Site and Organization in our method names changing something like "unsetGroupUsers" for "unsetSiteUsers" but I would suppose change a lot classes]

3, Unsetting organization users: do not remove the site roles for users belonging to the Site and the Organization in a explicit way.

Cheers.