Move ptvsd_launcher.py into this repo

[DonJayamanne]

VS Code would like to use the ptvsd_launcher.py file (found in VS) to launch the debugger.

This allows VS Code to share the logic found in the above script.

Based on conversation with Pavel here #40 (comment)

@karthiknadig Once this is done you'll need to update VS accordingly.

[DonJayamanne]

Should the same be done for the other ptvsd_* scripts?
Namely:

• ptvsd_loader.py
• ptvsd_repl_launcher.py

[int19h]

Loader is only used for direct local attach via thread injection; pydevd has its own way of doing this which is different (and which we still need to investigate).

The REPL script is for the REPL Python backend in the old debugger (that talks its own protocol). We might need something to replace it for REPL, but it definitely won't be the same script.

[brettcannon]

Been told by @DonJayamanne this has been done.

[DonJayamanne]

Fixed with microsoft/vscode-python#1373