[Overview Actions] Update the actions container UI.

Make the overview actions container not limited by the taskview any more, and add left and right margin as 16dp to it.

Screenshot: https://hsv.googleplex.com/5938979251683328
Test: local
Bug: 153591867
Change-Id: I8056105fe4c03311e473bb317cba345048ec2203
2 files changed