Move mdnsd policy to private

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

Test: No change to policy according to sesearch, except for
      disappearance of all allow rules to do with mdnsd_current (as
      expected).
Bug: 31364497

Change-Id: Ia4f01d91e7d593401e8cde2d796a0f1023f6dae4

private/mdnsd.te

-# type_transition must be private policy the domain_trans rules could stay
-# public, but conceptually should go with this
+# mdns daemon
+
+typeattribute mdnsd mlstrustedsubject;
+
+type mdnsd_exec, exec_type, file_type;
 init_daemon_domain(mdnsd)
+
+net_domain(mdnsd)
+
+# Read from /proc/net
+r_dir_file(mdnsd, proc_net)

public/mdnsd.te

 # mdns daemon
-type mdnsd, domain, mlstrustedsubject;
-type mdnsd_exec, exec_type, file_type;
-
-net_domain(mdnsd)
-
-# Read from /proc/net
-r_dir_file(mdnsd, proc_net)
+type mdnsd, domain;