Provide IntelliSense in DEBUG CONSOLE

[cateyes99]

Environment data

dotnet --info output:

.NET Command Line Tools (1.0.1)

Product Information:
 Version:            1.0.1
 Commit SHA-1 hash:  005db40cd1

Runtime Environment:
 OS Name:     Mac OS X
 OS Version:  10.11
 OS Platform: Darwin
 RID:         osx.10.11-x64
 Base Path:   /usr/local/share/dotnet/sdk/1.0.1

VS Code version: 1.13.1
C# Extension version: 1.11.0

Steps to reproduce

1. Debug a .NET Core application
2. Open DEBUG CONSOLE

Expected behavior

When typing in the DEBUG CONSOLE's command line, it should provide IntelliSense

Actual behavior

No IntelliSense provided

[gregg-miskelly]

@DustinCampbell suppose VS Code could somehow expose you the text position of the current statement. Any idea how hard it would be to hookup the language service so it could provide completion in the debug console?

[DustinCampbell]

Tricky, but not impossible. We'd also need the text of the debug console and then we'd have to stitch it in to the active document. I'd be a medium-level work item if we had all of that information.

[gregg-miskelly]

@DustinCampbell do you think that would be the right architecture? If so, should I open an issue in VS Code to request support now?

[DustinCampbell]

I don't know of another way to do it. That's essentially what we do in VS. The completion needs be based on the current state of the user's code augmented by whatever's in the debug console. Essentially, I would add to OmniSharp's completion end point to include the code from the debug console for speculative completion.

Yeah, we'll need help from VS Code, so we should open a request if there isn't one already.

[vchirikov]

Duplicate of #299

[gregg-miskelly]

This should be tracked with: #299