selftests/bpf: Expand sockaddr program return value tests

This patch expands verifier coverage for program return values to cover
bind, connect, sendmsg, getsockname, and getpeername hooks. It also
rounds out the recvmsg coverage by adding test cases for recvmsg_unix
hooks.

Signed-off-by: Jordan Rife <jrife@google.com>
Link: https://lore.kernel.org/r/20240510190246.3247730-15-jrife@google.com


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