selftests/net: Cover the IP_LOCAL_PORT_RANGE socket option

selftests/net: Cover the IP_LOCAL_PORT_RANGE socket option

Exercise IP_LOCAL_PORT_RANGE socket option in various scenarios:

1. pass invalid values to setsockopt
2. pass a range outside of the per-netns port range
3. configure a single-port range
4. exhaust a configured multi-port range
5. check interaction with late-bind (IP_BIND_ADDRESS_NO_PORT)
6. set then get the per-socket port range

Reviewed-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Signed-off-by: Jakub Sitnicki <jakub@cloudflare.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>