Add trace_to_text support for memory events
Add trace_to_text support for memory events

Best effort for now - does not handle complicated situations properly.
Specifically gfp_flags and the pfn for mm page events are not
outputted correctly.

Bug:117642698
Change-Id: I115f3de99c8a1068ab85b972d07b17be33d150b4

google/perfetto,google/perfetto,google/perfetto,google/perfetto,google/perfetto,google/perfetto,google/perfetto,google/perfetto