XWIKI-13845: Find a way to differentiate between the various ways to install XWiki in active install

XWIKI-13847: Create button not available for users which only have edit rights on a subtree in the wiki (and not on the whole wiki)

* Put back style removed by mistake.

XCOMMONS-1090: Cache and create instances of ExtensionDependency through a factory to reduce duplicates
XCOMMONS-1091: Cache and create instances of ExtensionAuthor through a factory to reduce duplicates
XCOMMONS-1103: Cache and create instances of Version through a factory to reduce duplicates

* Put back style removed by mistake. Thanks sdumitriu!