Rights management does not support properly user/group id with a comma

Pretty much the same reason than XWIKI-5149 except that this time it's more complex because the XWiki.XWikiGlobalRights and XWiki.XWikiRights classes are clearly (badly) designed to contains list of users/groups.

BTW having too different fields for groups and users is just ridiculous IMO, it should be one single member like in XWikiGroups object.

Reproduction steps:

• Create a group named "Comma," from the administration
• Create a page, go to administer it and check "View" to grant view right to the group "Comma,"
• Open the page in object edit mode and check the right object

Expected result:

• a right object is created containing "XWiki.Comma,"

Obtained result:

• a right object is created containing "XWiki.Comma" which is an unexisting group