Add getter methods of the python exception class

[spywo]

The code and message should be able to return. It keeps consistent with the API of C++. The naming conversion is also followed with python PEP 8.

[spywo]

For example, C++

try {}
catch (const AdProjectionSystem::EAdProjectionSystemException& e) {
    // Handle error with code and message
    auto errorCode = e.getErrorCode();
    auto errorMessage = e.getErrorMessage();
    
    if (errorCode == ADPROJECTIONSYSTEM_ERROR_CRS_NOT_FOUND) {
        // Provide localized message or fallback behavior
    }
}

The python should also have the similiar way:

try:
except AdProjectionSystem.EAdProjectionSystemException as e:
    error_code = e.GetErrorCode()
    error_message = e.GetErrorMessage()
    
    # Use error code for localization or display message directly
    handle_error(error_code, error_message)

[spywo]

The other language also has the issue, like Java.