Add button for opening Huawei battery settings during setup
This branch adds a button to the power management setup screen for Huawei devices running EMUI 8 or higher. The button opens the battery section of the system settings, as we can't open the App Launch screen directly.
I've tested the branch on devices running EMUI 9 and 10. I don't have a device running EMUI 8, but this Huawei Community post says that the App Launch screen exists on EMUI 8.
Part of #1743 (closed)