[dtests] refactor windows specific changes (#1313)

* [dtests] refactor windows specific changes

* Refactor hipMemoryAllocateCoherentDriver - PR- 1309

* Fix missing z in _putenv_s

* Revert "Fix missing z in _putenv_s"

This reverts commit 099a1b20a5c75c5f122d57c0ad2bca01745cdc9c.

* Refactor changes from PR 1299

* Update hipEnvVarDriver.cpp

tests/src/hipEnvVar.cpp

@@ -31,14 +31,7 @@ THE SOFTWARE.
 #include "clara/clara.hpp"
 #include <string>
 #include "hip/hip_runtime.h"
-
-#ifdef _WIN64
-#include <tchar.h>
-#endif
-
-#ifdef _WIN64
-#define setenv(x,y,z) _putenv_s(x,y)
-#endif
+#include "test_common.h"
 
 using namespace std;
 using namespace clara;