View rights are not propagated

In Confluence, view rights are propagated, and others rights aren't.

We need to propagate them during migration as well, by putting them in WebPreferences pages in nested migrations.

This is not possible in non nested migrations, which we should probably deprecate.

Confluence behaviors wrt rights we won't be able to reproduce in Standard XWiki:

• rights can only be further restricted. We can't open up rights in a sub page. When permissions are set to pages, they can only limit the number of users to which they grant rights. It's not possible to allow more people than those who can access parent pages. This means that if on Page A, VIEW restriction is set for Group A, and on Sub Page B, VIEW right is set for Group B, only people that are both in Group A and in Group B are allowed to see Sub Page B. It is not enough to be in Group B. We'll have to do with the fact that the migrated Sub Page B will be allowed to the whole Group B, and we'll document this discrepancy between Confluence and XWiki, unless someone is willing to setup custom right management in XWiki, which is not advisable in most cases and can surprise users who already know XWiki, and support teams
• edit rights can be granted to users on pages , but they won't be able to edit those pages if they don't have edit permissions on the space.

In XWiki, by default, rights will be opened up. All users of group be will be able so see Sub Page B, and a user will be able to edit a page if edit right is set for this user, even if the user didn't have edit rights on the space in Confluence.