Add the ability to debug Xunit tests.

[PradeepLoganathan]

Environment data

dotnet --info output:
Version: 1.0.0-preview2-003121
Commit SHA-1 hash: 1e9d529bc5

Runtime Environment:
OS Name: Windows
OS Version: 10.0.14393
OS Platform: Windows
RID: win10-x64

• VSCode Version: Code 1.7.2 (7ba55c5860b152d999dda59393ca3ebeb1b5c85f, 2016-11-21T22:06:37.428Z)
• OS Version: Windows_NT ia32 10.0.14393
• Extensions:

Extension	Author	Version
html-snippets	abusaidm	0.0.18
githistory	donjayamanne	0.1.0
javadebugger	donjayamanne	0.0.2
rest-client	humao	0.10.4
Angular2	johnpapa	1.0.2
csharp	ms-vscode	1.5.0-beta8
vscode-docker	PeterJausovec	0.0.7
java	redhat	0.0.7

I don't see an option to debug xunit tests. after creating tests in xunit I am able to run it successfully against my target library. I am unable to debug tests since the debug option is expecting a main entry point.

[DustinCampbell]

My apologies for letting this grow so stale. Here is the current state of the world:

• This should work with project.json-based .NET Core projects.
• There is a bug with detecting xUnit tests defined in nested classes that should be fixed in 1.7. (Failed to run test because null with nested test classes.  #1151)
• This does not work with .csproj-based .NET Core projects yet. This is a fairly large work item to fix and we're planning to do it for the 1.8 release. (Implement VSTest support to enable running and debugging .NET Core tests in .csproj projects #1100)

I'm going to go ahead and close this issue as the work is being tracked elsewhere.