Carry the ClickHouse patches onto v3.13.0

[actueleai]

Rebases the ClickHouse patches of nats-io onto upstream tag v3.13.0 (78981ed5). Two commits are carried, cherry-picked with -x and keeping their original authors: "Merge pull request #2 from tchepavel/patch-1" (Alexey Milovidov — include <sys/socket.h> in n-unix.h on FreeBSD) and "Merge pull request #3 from tavplubix/fix_build_clang_15" (Ivan Blinkov — add <stdio.h> to n-unix.h, and include natsp.h before <ctype.h> in js.c and kv.c so _GNU_SOURCE is defined before the first system header). Both applied cleanly, with no conflicts.

Two patches are dropped as obsolete. "Merge pull request #1 from tchepavel/main" (Alexey Milovidov) replaced libc rand with an OpenSSL RAND_bytes-based _rand32; v3.13.0 no longer calls rand in src/ at all, using nats_Rand64 and a seeded CMWC generator instead. "Remove legacy OpenSSL API usage" (Konstantin Bogdanov) dropped ERR_remove_thread_state, TLSv1_2_client_method and the NATS_USE_OPENSSL_1_1 branches, none of which exist upstream anymore. The remaining commits in the GitHub compare are upstream release_3_9 branch commits, not ClickHouse patches.

Once merged, ClickHouse's contrib/nats-io submodule is bumped to this branch head.