Merge "Make some fstab functions available outside of fs_mgr" into main am: 6e1b4c5a

Original change: https://android-review.googlesource.com/c/platform/system/core/+/3200691



Change-Id: I37940d837a59a413930fbd5a7924dd84518b76f2
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>