UI support for TimeTravel Debugging for Node

[aruneshchandra]

Node-ChakraCore has been working on bringing TTD to Node.js developers with the idea to surface this feature using VSCode.

Hitting a breakpoint and stepping forward is a familiar experience, but TTD allows developers to step back after hitting the breakpoint. For this new UI affordance needs to be built in VSCode, for example a "StepBack" button on the debug bar. Ideally this new button could be conditional based on a capability detection of the underlying Node platform.

Adding this support in VSCode will help us bring this innovation to the node developers.

[roblourens]

If it's useful at all, this was prototyped in https://github.com/roblourens/vscode/commits/stepback and https://github.com/roblourens/vscode-node-debug/commits/stepback

[weinand]

@isidorn I've added protocol support for this (and I will enable it in mock-debug).
Please add UiI support for this.

[isidorn]

Moved here microsoft/vscode#7652 since it is easier for me to track issues in our main vscode repo