Move microdroid sepolicy to system/sepolicy

Bug: 190511750
Test: boot microdroid
Change-Id: I4aa4a56e9be5103d70469c3508110a973f3e4f12
diff --git a/microdroid/system/private/toolbox.te b/microdroid/system/private/toolbox.te
new file mode 100644
index 0000000..a2b958d
--- /dev/null
+++ b/microdroid/system/private/toolbox.te
@@ -0,0 +1,3 @@
+typeattribute toolbox coredomain;
+
+init_daemon_domain(toolbox)