[Launcher] Indicate number of open windows

[donovanglover]

Is your feature request related to a problem? Please describe. Would be cool if there was a way to indicate how many windows are open similar to dash-to-panel.

Describe the solution you'd like Applications have dots/underlines indicating how many windows of an application are open. Not sure if this would require the logic to be separate from the user's CSS.

Describe alternatives you've considered Different CSS classes depending on the number of windows. Might only need an indicator for "more than one window".

Additional context