Enable "ISE Mode" at the workspace scope

[alexandair]

Summary of the new feature

At the moment, ISE Mode could be enabled globally, changing the global VSCode settings.
User should be able to enable it at the workspace scope, so that global settings are not changed, and only certain workspace is affected.

[TylerLeonhardt]

I think this is reasonable. It'd be really easy to add too.

Add to this method:

vscode-powershell/src/features/ISECompatibility.ts

Line 48 in 94f3624

private async EnableISEMode() {

and use this API:

vscode.window.showQuickPick(["Modify settings for this user.", "Modify settings for this workspace."], ...)

The phrases I'm not 100% on yet... but it's a very simple code change.

cc @corbob who originally did ISE Mode