I don't think this is an idea worth pursuing. Ignition's named queries have their own parameter syntax which is unlikely to work in Visual Studio. In addition,
Your best bet would be to develop your SQL in whatever environment you want and then paste it into Ignition's Named Query editor, fix the parameters and test it there.
Regarding your error message, the user that VSC is running under doesn't appear to have rights to the Ignition folder. That's a Windows permissions issue.