Move system property rules to private

public/property split is landed to selectively export public types to
vendors. So rules happening within system should be in private. This
introduces private/property.te and moves all allow and neverallow rules
from any coredomains to system defiend properties.

Bug: 150331497
Test: system/sepolicy/tools/build_policies.sh
Change-Id: I0d929024ae9f4ae3830d4bf3d59e999febb22cbe
Merged-In: I0d929024ae9f4ae3830d4bf3d59e999febb22cbe
(cherry picked from commit 42c7d8966cc5f76c84c001c5af787cbfade736c8)
diff --git a/private/mediaswcodec.te b/private/mediaswcodec.te
index 50f5698..cef802d 100644
--- a/private/mediaswcodec.te
+++ b/private/mediaswcodec.te
@@ -2,3 +2,4 @@
 
 init_daemon_domain(mediaswcodec)
 
+get_prop(mediaswcodec, device_config_media_native_prop)