ANDROID: mm: Memory health driver

Android has no-event driven way to know when certain memory conditions
occur, or memory management actions take place. This new memory health
driver will start capturing these cases, starting by keeping track of
out-of-memory (OOM) victims.

To access the list of OOM victims, the driver provides a proc file
named "oom_victim_list" in the "/proc/memhealth" directory. The
proc file supports sequential reading and polling.

Merged aosp/2755185 in this change since `list_count_nodes` is not available in android-15-6.1.

Bug: 244232958
Change-Id: Ica5dcb4dc42229d85828f0e495a43d22390927f1
Signed-off-by: Carlos Galo <carlosgalo@google.com>