[libc] Implement getsockopt and setsockopt on linux (#192237)

This patch implements getsockopt and setsockopt socket functions on
Linux. It follows the established pattern of wrapping socketcall or
using direct syscalls.

I added a basic test setting a couple of options.

I only added the first couple of simple constants (e.g. whose value does
not depend on the architecture). I've left the others for a separate
patch.

GitOrigin-RevId: 10be669bc5a8c6b8b988f3e91760f9d7c391e246