### Description
Refactor the cmake code that is related to delay loading. Provide a
cmake option to control if delay loading should be enabled or not.
Disabling the option when python is enabled, due to a known issue.
### Motivation and Context
ONNX Runtime's python package depends on DirectML.dll, but supposedly
the DLL should be delay loaded.
This PR only refactor the code. It doesn't change the behavior.