Add microdroid specific sepolicy

Microdroid will have a separate sepolicy, apart from the core policy.
This is the first step; For now it's a simple copy of system/sepolicy.
For the future work, it will be stripped.

Bug: 189165759
Test: boot microdroid and see selinux enforced
Change-Id: I2fee39f7231560b49c93bd5e8d0feeffada40938
diff --git a/microdroid/sepolicy/system/private/uncrypt.te b/microdroid/sepolicy/system/private/uncrypt.te
new file mode 100644
index 0000000..1a94cd1
--- /dev/null
+++ b/microdroid/sepolicy/system/private/uncrypt.te
@@ -0,0 +1,6 @@
+typeattribute uncrypt coredomain;
+
+init_daemon_domain(uncrypt)
+
+# Set a property to reboot the device.
+set_prop(uncrypt, powerctl_prop)