activitymanager: Fix header item and missing porting bits

Fix the mistaken port of the local component Heading to Kirigami (yeah, the naming here was quite confusing) and bring back the filter capability.

BEFORE	AFTER

While at it finish porting some small bits.

• Port from KQuickControlAddons.KCMShell to KCMUtils.KLauncher
• Fix remaining s/KAuthorize/KAuthorized/ usage.

Amends d4593b3d

CC: @noee