XWIKI-9708: Repair phase is not executed nor prompted on subwikis when Upgrade All Wikis option is selected from DW
* Add a method to the distribution script service to get the distribution state for a subwiki
* Make the repair UI generic so that it can be reused on the 'Wikis' step
* Add templates/distribution/macros.vm to hold Velocity macros that are shared by multiple steps
* Fix the XAR repair macro in extension.vm as it was working only for the current wiki