build: update to not need _CRT_NONSTDC_NO_DEPRECATE with MSVC

Use non-deprecated CRT function variants on Windows.

- introduce `curlx_fdopen()`, `curlx_close()` and use them. Map them to
  non-deprecated, underscored, CRT functions on Windows.

- replace `close()` uses with either `sclose()` (for sockets) or
  `curlx_close()` (for files).

- map `fileno`, `unlink`, `isatty` to their non-deprecated, underscored,
  versions on Windows.

- tool_dirhie: map `mkdir` to `_mkdir` on Windows.

- easy: use `_strdup()` on Windows, regardless of how `HAVE_STRDUP` is
  set.

- cmake: assume `HAVE_STRDUP` on Windows. To allow dropping a detection
  hack using `_CRT_NONSTDC_NO_DEPRECATE` with MSVC. Windows always has
  `_strdup()` which the code uses, but also needs `HAVE_STRDUP` defined
  to disable curl's own `strdup()` implementation.

- curl_setup.h: drop `_CRT_NONSTDC_NO_DEPRECATE` as no longer necessary.

Closes #20212

lib/cf-socket.c

@@ -349,7 +349,7 @@ static CURLcode socket_open(struct Curl_easy *data,
   if(fcntl(*sockfd, F_SETFD, FD_CLOEXEC) < 0) {
     failf(data, "fcntl set CLOEXEC: %s",
           curlx_strerror(SOCKERRNO, errbuf, sizeof(errbuf)));
-    close(*sockfd);
+    sclose(*sockfd);
     *sockfd = CURL_SOCKET_BAD;
     return CURLE_COULDNT_CONNECT;
   }