mw.Upload.BookletLayout: Correct some message parameters

• 'fileexists', 'filepageexists': Requires prefixed page name.
• 'api-error-duplicate', 'api-error-duplicate-archive': Takes the number of duplicates, not name of duplicate. The list of duplicates is supposed to follow this message.

Change-Id: Idfa978469f4a99526100f6c24a67bf18abf7ec89