Fix RNG crash on Windows (#2871)

This PR adds a Windows workaround for a crash on Battlemage during test
runs.

In oneMKL 2026.0 `mkl_rng::mt19937` destructor may crash with
`STATUS_STACK_BUFFER_OVERRUN` during `DLL_PROCESS_DETACH` when using the
Level Zero backend and static storage inside a DLL.

The workaround heap-allocates `backend_sycl` singleton on Windows to
avoid running its destructor at shutdown. Although `~backend_sycl()` is
empty, it triggers destruction of its members (including
`mkl_rng::mt19937`) which causes the crash.
Since `backend_sycl` is a process-lifetime singleton, skipping its
destruction is safe because OS reclaims all
resources at process exit.

Author: vlad-perevezentsev

dpnp/backend/src/queue_sycl.hpp

@@ -67,8 +67,17 @@ class backend_sycl
 
     static backend_sycl &get()
     {
+#if defined(_WIN32) && INTEL_MKL_VERSION == 20260000
+        // TODO: remove once MKLD-19835 is resolved
+        // mt19937 (oneMKL 2026.0) destructor crashes during DLL_PROCESS_DETACH
+        // on Windows (Battlemage/Level Zero). Use a heap-allocated
+        // process-lifetime singleton to skip destructor; OS reclaims memory.
+        static backend_sycl *backend = new backend_sycl{};
+        return *backend;
+#else
         static backend_sycl backend{};
         return backend;
+#endif
     }
 
     static sycl::queue &get_queue()