XWIKI-8748:  When an extension is installed on several wikis "Upgrade on farm" should upgrade the extension only on theses wikis
* Check all extension actions even if a form token is provided, but execute 'continue' and 'repairXAR' only if a valid token is provided. Otherwise extensions actions (like recomputing the install plan) have no effect when the continue button is present.
(cherry picked from commit 6ba7a6bd12a6120fe2e6e5c12bb06d62eb345d4e)