Fix height and top padding of shade header and keyguard status bar

Values are now read from a central place, instead of directly from
resources.
Top padding is now also accounted for, which was introduced recently.

Flag: ACONFIG com.android.systemui.centralized_status_bar_dimens_refactor DISABLED
Fixes: 317016114
Fixes: 317016116
Test: Manual and unit tests
Change-Id: I339d3159f0b82a4118ae3e34c99c57e87990eb07