build: do not include wolfSSL header in curl_setup.h

[vszakats]

To fix building tests/server with cmake and both wolfSSL and OpenSSL
enabled (MultiSSL).

tests/server do not have libcurl dependency header paths setup because
it does not use libcurl. The code however includes curl_setup.h, which
tried including wolfssl/version.h before this patch to verify if the
wolfSSL coexist feature is available. Without a header path, it failed:

In file included from bld/tests/server/servers.c:3:
In file included from tests/server/first.h:40:
lib/curl_setup.h:737:12: fatal error: 'wolfssl/version.h' file not found
  737 | #  include <wolfssl/version.h>
      |            ^~~~~~~~~~~~~~~~~~~
1 error generated.

Ref: https://github.com/curl/curl/actions/runs/22410066319/job/64880787424#step:46:76

Fix by moving the include and version check to vtls/wolfssl.c.

Also: add an early version check to cmake.

Follow-up to 16f073e #16973
Cherry-picked from #20720