Invalid json test cases + strings validation (#1558)

* added tests for invalid json types
* guid strings validation
* device id validation

src/modules/fancyzones/lib/JsonHelpers.h

@@ -16,6 +16,11 @@ namespace JSONHelpers
 {
     constexpr int MAX_ZONE_COUNT = 50;
 
+    #if defined(UNIT_TESTS)
+    bool isValidGuid(const std::wstring& str);
+    bool isValidDeviceId(const std::wstring& str);
+    #endif
+
     enum class ZoneSetLayoutType : int
     {
         Blank = -1,