Add test cases for enabled status of DolphinNewFileMenu

Summary:
Root and Trash test cases are currently failing because of
commit e133c4557ecc37ed3f7e1b9418306aa8cc516865.

Reviewers: Dolphin

Subscribers: kfm-devel

Tags: Dolphin

Differential Revision: https://phabricator.kde.org/D16005