ProjectExplorer: Move environment "Batch Edit" button up

It was often enough below the visible area of the view
and people did not notice it exists.

Change-Id: Ie1427c3cb90b6d4a200a17cf51402aabc51de7e7
Reviewed-by: Jarek Kobus <jaroslaw.kobus@theqtcompany.com>
Reviewed-by: Eike Ziller <eike.ziller@theqtcompany.com>