Verify end state of document in cohosting completion tests

[davidwengier]

Cohosting allows us to have tests for override completion, which makes a complex edit. Our current test only verifies that items appear in completion, but we've never have a bug around that. What we have had multiple times though, is bugs around the application of the edits for completion. That is currently untested, and we should fix that.

[alexgav]

I'm not seeing edits coming from C# for this case. I did look at this for the test case I added.