Create an event_log_tags_file label and use it for
/dev/event-log-tags.  Only trusted system log readers are allowed
direct read access to this file, no write access.  Untrusted domain
requests lack direct access, and are thus checked for credentials via
the "plan b" long path socket to the event log tag service.

Test: gTest logd-unit-tests, liblog-unit-tests and logcat-unit-tests
Bug: 31456426
Bug: 30566487
Change-Id: Ib9b71ca225d4436d764c9bc340ff7b1c9c252a9e

reflect the change from "mediaanalytics" to "mediametrics"

Also incorporates a broader access to the service -- e.g. anyone.
This reflects that a number of metrics submissions come from application
space and not only from our controlled, trusted media related processes.
The metrics service (in another commit) checks on the source of any
incoming metrics data and limits what is allowed from unprivileged
clients.

Bug: 34615027
Test: clean build, service running and accessible
Change-Id: I657c343ea1faed536c3ee1940f1e7a178e813a42

This leaves only the existence of platform_app domain as public API.
All other rules are implementation details of this domain's policy and
are thus now private.

Test: No change to policy according to sesearch, except for
      disappearance of all allow rules from platform_app_current
      attribute (as expected).
Bug: 31364497

Change-Id: I47bb59fdfc07878c91fd5e207735cd0c07a128da

Because I'm nitpicky.

Test: policy compiles
Change-Id: I4d886d0d6182d29d7b260cf1f142c47cd32eda29

app_domain was split up in commit: 2e00e637 to
enable compilation by hiding type_transition rules from public policy.  These
rules need to be hidden from public policy because they describe how objects are
labeled, of which non-platform should be unaware.  Instead of cutting apart the
app_domain macro, which non-platform policy may rely on for implementing new app
types, move all app_domain calls to private policy.

(cherry-pick of commit: 76035ea0)

Bug: 33428593
Test: bullhead and sailfish both boot. sediff shows no policy change.
Change-Id: I4beead8ccc9b6e13c6348da98bb575756f539665

In order to support platform changes without simultaneous updates from
non-platform components, the platform and non-platform policies must be
split.  In order to provide a guarantee that policy written for
non-platform objects continues to provide the same access, all types
exposed to non-platform policy are versioned by converting them and the
policy using them into attributes.

This change performs that split, the subsequent versioning and also
generates a mapping file to glue the different policy components
together.

Test: Device boots and runs.
Bug: 31369363
Change-Id: Ibfd3eb077bd9b8e2ff3b2e6a0ca87e44d78b1317