Fix interpolation in Log points, switch to double quotes

[rkeithhill]

Fix PowerShell/vscode-powershell#2654

When this works you can do some fancy stuff like timing loops:

This uses messages:

Init loop var: $($global:prevTS = Get-Date; $prevTS)
Loop time: $($currTS = Get-Date; ($currTS - $prevTS).TotalMilliseconds; $global:prevTS = $currTS) ms

[rkeithhill]

I don't think the build errors are associated with this change:

  X PowerShellEditorServices.Test.E2E.LanguageServerProtocolMessageTests.CanReceiveDiagnosticsFromFileChanged [3s 18ms]
  Error Message:
   The collection was expected to contain a single element, but it contained more than one element.
  Stack Trace:
     at PowerShellEditorServices.Test.E2E.LanguageServerProtocolMessageTests.CanReceiveDiagnosticsFromFileChanged() in D:\a\1\s\test\PowerShellEditorServices.Test.E2E\LanguageServerProtocolMessageTests.cs:line 190
--- End of stack trace from previous location where exception was thrown ---

[TylerLeonhardt]

It's not you

[TylerLeonhardt]

LGTM

[TylerLeonhardt]

yay logpoints! 🎉