selftests/bpf: Add selftest for sockmap/hashmap redirection

Test redirection logic. All supported and unsupported redirect combinations
are tested for success and failure respectively.

BPF_MAP_TYPE_SOCKMAP
BPF_MAP_TYPE_SOCKHASH
	x
sk_msg-to-egress
sk_msg-to-ingress
sk_skb-to-egress
sk_skb-to-ingress
	x
AF_INET, SOCK_STREAM
AF_INET6, SOCK_STREAM
AF_INET, SOCK_DGRAM
AF_INET6, SOCK_DGRAM
AF_UNIX, SOCK_STREAM
AF_UNIX, SOCK_DGRAM
AF_VSOCK, SOCK_STREAM
AF_VSOCK, SOCK_SEQPACKET

Suggested-by: Jakub Sitnicki <[email protected]>
Signed-off-by: Michal Luczaj <[email protected]>
Signed-off-by: Martin KaFai Lau <[email protected]>
Acked-by: John Fastabend <[email protected]>
Link: https://lore.kernel.org/r/[email protected]

Author: mmhal