Provide parameters to enable or disable linking to user profiles in the user displayer

The same applies to groups, displayed through the group displayer.

This is particularily interesting if we want to rely on the standard user & group displayers as part of XWIKI-21306, in order to keep the current behavior in subwikis :
When a sub-wiki is configured to allow users and groups from the main wiki and the sub-wiki itself, we would need to not show a link to the user / group document if the user / group comes from the main wiki.