Replace the current toolbar implementation with the new PageHeader component on the (rails) global index pages

* Begin of the insertion[x]End of the insertion Begin of the deletion [ ]End of the deletion Homepage
* Begin of the insertion[x]End of the insertion Begin of the deletion [ ]End of the deletion Activity
* Begin of the insertion[x]End of the insertion Begin of the deletion [ ]End of the deletion Calendar (index page)
* Begin of the insertion[x]End of the insertion Begin of the deletion [ ]End of the deletion Boards (index page)
* Begin of the insertion[x]End of the insertion Begin of the deletion [ ]End of the deletion Team planner (index page)
* Begin of the insertion[x]End of the insertion Begin of the deletion [ ]End of the deletion News
* Begin of the insertion[x]End of the insertion Begin of the deletion [ ]End of the deletion Time and costs