Support for customizing exception breakpoints in debugger

[DonJayamanne]

Today the debugger supports breaking into specific exceptions by listing the exceptions in the launch.json file.
Now that PTVSD supports the protocol, Its a good time to visit how these custom exception breakpoints can be passed into PTVSD, here's are the two solutions:

Option 1: Note: We'd need to add lot more exceptions into the list,
Option 2: Go with the launch.json approach (configure exceptions in the launch.json as done today - no GUI).

here's option 1:

@MikhailArkhipov @brettcannon @qubitron cc

[qubitron]

@DonJayamanne I think listing all possible exceptions types will be overloading the UI too much, and not clear how it would work for user defined exception types. Ideally you could add exceptions to this list, similar to how the add function breakpoint works, though I assume this would require upstream work from VS Code to support. I'm thinking the "+" button would show a menu allowing you to choose between "Add Function Breakpoint" and "Add Exception Breakpoint". Upon selecting "Add Exception Breakpoint" you could then type in the exception name you wanted.

If we can't do the above, then I'd stick with launch.json. To improve discoverability we could add a checkbox in the list above that turns break on specific exceptions on/off, named something like "Exceptions Specified in launch.json". This would also allow you to turn off the exception breakpoints mid-debug session if they are hitting too often & getting in your way.

[DonJayamanne]

Here's how its configured in the Mono debugger (from Msft):

• They are configured per workspace, not per debug configuration
• Settings stored in settings.json instead of launch.json
• Settings can be managed via gui (see below)