Lazily initialize GlobalAdapter (#21490)

**Problem**
`ur_win_proxy_loader` loads L0 adapter DLL in its `DLLMain`. Global
variables are initialized during DLL loading and so is `GlobalAdapter` -
which tries to initialize L0 driver (`zeInit`). `zeInit` may spawn
threads and it's illegal to spawn threads directly or indirectly from
`DLLMain`.
This is causing deadlock with some L0 driver versions.

**Proposed Solution**
Lazily initialize `GlobalAdapter`, just like what we do on Linux.

Author: uditagarwal97

source/adapters/level_zero/adapter.cpp

@@ -22,14 +22,8 @@
 #endif
 
 ZeUSMImportExtension ZeUSMImport;
-
-// Due to multiple DLLMain definitions with SYCL, Global Adapter is init at
-// variable creation.
-#if defined(_WIN32)
-ur_adapter_handle_t_ *GlobalAdapter = new ur_adapter_handle_t_();
-#else
 ur_adapter_handle_t_ *GlobalAdapter;
-#endif
+
 // This is a temporary workaround on windows, where UR adapter is teardowned
 // before the UR loader, which will result in access violation when we use print
 // function as the overrided print function was already released with the UR