Currently, there is a hetero runtime property that darwinn
and other hetero runtime project will use: the trace level
(vendor.google.silicon.max_trace_level).
This change allows edgetpu services and clients to be able to see
that property in order to change the trace level.
Bug: 272292650
Test: verified it to build but not tested on device yet since selinux
has not been enforced yet.
Change-Id: Id6d345b92d2e710b41ca58907ad443fc2667054a
8e965d36a2