LPS-44924 - On mobile devices, there should be a success message when a portlet has been added to a page.

Hi @jonmak08,

This is a potential fix for LPS-44924.  There was a short discussion and a couple gifs (https://zulip.com/#narrow/stream/engineering-ui/topic/mobile.20-.20feedback.20when.20adding.20an.20app) on zulip about how we could handle this 'success message'.  And this fix is what me and Marc thought looked the best.  

Please let me know your thoughts.

Thanks!