LaunchSettingsProvider doesn't handle when the AppDesignerFolder changes

[davkean]

LaunchSettingsProvider caches the AppDesignerFolder/LaunchSettingsFile location - when that changes, so should it.

[davkean]

It's also mixing live project data with dataflow.

[davkean]

We should move this completely to data flow, see: https://devdiv.visualstudio.com/DevDiv/_workitems/edit/461771?fullScreen=false for more information.