openssl: remove attached easy handles from SSL instances

- keeping the "current" easy handle registered at SSL* is no longer
   necessary, since the "calling" data object is already stored in the
   cfilter's context (and used by other SSL backends from there).
 - The "detach" of an easy handle that goes out of scope is then avoided.
 - using SSL_set0_wbio for clear reference counting where available.

Closes #10151

configure.ac

@@ -4217,6 +4217,13 @@ if test "x$want_ech" != "xno"; then
   fi
 fi
 
+dnl *************************************************************
+dnl check whether OpenSSL (lookalikes) have SSL_set0_wbio
+dnl
+if test "x$OPENSSL_ENABLED" = "x1"; then
+  AC_CHECK_FUNCS([SSL_set0_wbio])
+fi
+
 dnl *************************************************************
 dnl WebSockets
 dnl