Add a settings key to expose the device's repair mode state am: 0e1d0ecf51 am: 14cb34fa23

Original change: https://android-review.googlesource.com/c/platform/frameworks/base/+/2781891

Change-Id: Ib7cf46d7c1524ca437359267e1dd82805ed18748
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>