Type completion with tooltips

[AspenForester]

Resolves PowerShell/vscode-powershell#2898
Adds tool tips for type completions, tests for completion are included.

[TylerLeonhardt]

hmm the Windows failures are different than the Windows failures...

[TylerLeonhardt]

So apparently CompletionType.Namespace is a thing... which would be System.Collections where as CompletionType.Type is System.Collections.ArrayList so you should also have a:

case CompletionType.Namespace:

[TylerLeonhardt]

This test passes in PS7 but fails in Windows PowerShell

[AspenForester]

Unfortunately, I don't understand why the tests fail. The two I created with @TylerLeonhardt's assistance seem to follow the model of the existing tests, but the completions results come back empty for the example provided for type completion.

[TylerLeonhardt]

A whole lot of nonsense for two lines of code... Thanks for putting up with the headache @AspenForester. Not sure why the tests don't work on Windows PowerShell but at least we'll have coverage for other PowerShell's and you confirmed it worked for Windows PowerShell manually...

I've opened #1355 to track the test weirdness.

[TylerLeonhardt]

CI is green so I'm merging.