Add additional meminfo fields to SystemMemory

This change adds 13 additional fields from /proc/meminfo to the
SystemMemory atom (MemTotal, MemFree, MemAvailable, Active, Inactive,
Active(anon), Inactive(anon), Active(file), Inactive(file), SwapTotal,
SwapFree, CmaTotal, CmaFree). This is intended to provide a view of
overall system memory usage.

7 of these fields were newly added to the Debug class.

Test: statsd_testdrive 10092; verify that new fields are populated.
Bug: 260245141
Change-Id: I2da2732a6f6153e67a03d8b2f616627ca13935c7