Remove WarehouseOverviewTabs from warehouse, storage

Those had almost no content and were too small to display all tab
buttons in their tab area. Now sporting account tabs instead.

This also changes the icon of AccountTab to the overview tab one!

Conflicts:
	content/objects/buildings/storagetent.yaml
	content/objects/buildings/warehouse.yaml
	horizons/gui/tabs/mainsquaretabs.py
Add collector utilization to tab_account

This retires WarehouseOverviewTab and its layout file overview_warehouse.

Conflicts:
	content/gui/xml/ingame/tabwidget/warehouse/tab_account.xml
	horizons/gui/tabs/buildingtabs.py
	horizons/gui/tabs/mainsquaretabs.py