Wire up the progress stream to the withProgress API

[JustinGrote]

Summary of the new feature
When a script is running, if it emits Progress stream output, that output should be tied to the withProgress API to show a toast of the scripts progress.

Low priority now that psreadline progress works fairly normally, this would be a "good first issue" or "nice to have" level item.

Proposed technical implementation details (optional)

https://github.com/microsoft/vscode-extension-samples/tree/master/progress-sample

Previously discussed in #140

[TylerLeonhardt]

In the past, we've talked about this but decided against it because it would be different from the Console experience - we generally want the PSIC to behave like the regular console.

Now that there's this full fledged API for progress in LSP, it might be a fun feature add if it looks nice.

Might be kinda tough to implement... but here's the progress code:

https://github.com/PowerShell/PowerShellEditorServices/blob/8c500ee1752201d3c1cc2e5d90f1a2af3b1eb15d/src/PowerShellEditorServices/Services/PowerShellContext/Session/Host/EditorServicesPSHostUserInterface.cs#L591-L666

This would absolutely have to handle nested progress.

[SeeminglyScience]

At the very least a $psEditor API for it would be cool. Doesn't translate super well to other editors though.