ggml : disable warnings for tests when using MSVC (#1273)

ggml : disable warnings for tests when using MSVC (#1273)

* ggml : disable warnings for tests when using MSVC

This commit disables warnings for tests on windows when using MSVC.

The motivation for this is that this brings the build output more
inline with what Linux/MacOS systems produce.

There is still one warning generated for the tests which is:
```console
  Building Custom Rule C:/ggml/tests/CMakeLists.txt
cl : command line  warning D9025: overriding '/DNDEBUG' with '/UNDEBUG'
[C:\ggml\build\tests\test-arange.vcxproj]
  test-arange.cpp
  test-arange.vcxproj -> C:\ggml\build\bin\Release\test-arange.exe
```

* ggml : fix typo in tests disable list