Automatically Generate launch.json based on File/Project

[Anapo14]

From user feedback: " The biggest pain is getting the debug environments set up, if there was a smart way to speed that up/automate it so I could just jump in and debug the current file automatically, that'd be neat."

I think this would also be an awesome feature that we could get to work for even the most basic Python scripts first. Automatically detect the project structure/file structure and automatically select the appropriate configuration for the user upon first debug.

Would be even more interesting if we could get it to work for django/flask, etc.

[karthiknadig]

This is something that the extension can address the best. By the time the debugger gets involved the launch json is already set.

[DonJayamanne]

Related if not a dup of #1179
Also see #2710

[luabud]

Dupe of #1179.