Grant access to icmp_socket to netdomain. This was previously
labeled as rawip_socket which apps are allowed to use. Neverallow
all other new socket types for apps.

Kernels versions > 4.9 redefine ICMP sockets from rawip_socket
to icmp_socket. To pass neverallow tests, we need to define
which IOCTLs are allowed (and disallowed).

Note that this does not change behavior on devices with
kernel versions <=4.9. However, it is necessary (although not
sufficient) to pass CTS on kernel version 4.14.

Bug: 110520616
Test: Grant icmp_socket in net.te and build.
Change-Id: I5c7cb6867d1a4cd1554a8da0d55daa8e06daf803