Add ProcessMemoryHighWaterMark atom

Collection of the RSS high-water mark is moved to a separate atom to
improve performance, increase flexibility and overcome security
constrainsts.
Performance: avoid reading /proc/pid/status in ProcessMemoryState;
flexibility: allow pulling RSS high-water mark on a different schedule;
security: add single point where we can trigger the high-water mark
reset.
The RSS high-water mark will be removed from ProcessMemoryState and
NativeProcessMemoryState atoms in a followup-up CL to ensure that the
collected data is continuous.

Bug: 119598534
Test: atest UidAtomTests#testProcessMemoryHighWaterMark
Change-Id: I52da7b5e695f771f1551e1f6a6a773bded4504d1