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/uncrypt.te b/private/uncrypt.te
index e4e9224..1a94cd1 100644
--- a/private/uncrypt.te
+++ b/private/uncrypt.te
@@ -1,3 +1,6 @@
 typeattribute uncrypt coredomain;
 
 init_daemon_domain(uncrypt)
+
+# Set a property to reboot the device.
+set_prop(uncrypt, powerctl_prop)