SEPolicy: Changes for new stack dumping scheme.

Applications connect to tombstoned via a unix domain socket and request
an open FD to which they can write their traces. This socket has a new
label (tombstoned_java_trace_socket) and appdomain and system_server are
given permissions to connect and write to it.

Apps no longer need permissions to open files under /data/anr/ and
these permissions will be withdrawn in a future change.

Bug: 32064548
Test: Manual

Merged-In: I70a3e6e230268d12b454e849fa88418082269c4f
Change-Id: Ib4b73fc130f4993c44d96c8d68f61b6d9bb2c7d5