selftests/bpf: Migrate wildcard destination rewrite test

Migrate test case from bpf/test_sock_addr.c ensuring that sendmsg
respects when sendmsg6 hooks rewrite the destination IP with the IPv6
wildcard IP, [::].

Signed-off-by: Jordan Rife <jrife@google.com>
Link: https://lore.kernel.org/r/20240510190246.3247730-10-jrife@google.com


Signed-off-by: Alexei Starovoitov <ast@kernel.org>