The Wiki Index should only list wiki I can access or open for invitation

In the Wiki Index, every wikis are listed.

But there are some wikis where you do not have view right and the ability to join them neither.

So, there is no reason to show them.

Use Case 1:

• in a farm, we host the wiki of company A and the wiki of company B, which are competitors. Maybe, B does not want A to know that their wiki is hosted on the same farm.

Use Case 2:

• when I create a template, as an admin, I might not want to allow any users to modify it. In this case, I remove all rights for them, and the template is not listed for users. In the same time, we fix XWIKI-9690