Deprecation: #84145 - Deprecate ext_isLinkable 

See forge#84145

Description 

The method TYPO3\CMS\Backend\Tree\View\ElementBrowserFolderTreeView->ext_isLinkable() has been marked as deprecated. It always returned true and still does it until removed.

Impact 

Little to no impact in extensions, the method behavior usually does not change.

Affected Installations 

Extensions extending the folder tree of the element browser may be affected but still should not change their behavior. Extension scanner may find usages and marks them as weak match since the methods appears in other classes as well.

Migration 

Don't call ext_isLinkable() anymore and assume true as return value.