net: socket: extend posix compatability SO_<opts>

Adding these definitions help ease of porting POSIX applications.

They currently do nothing in the core network stack and will
return an error if used. However, they help port some POSIX
without changing these. In particular, this enables using the
Nim programming language's standard library with Zephyr.

- The values copy Linux amd64, similar to the other SO_OPTIONS
- Add SO_SNDBUF to fix simplelink wifi
- Use compat options in simplelink wifi

Signed-off-by: Jaremy J. Creechley <jaremy.creechley@panthalassa.com>