Completed set notification

[clafalco]

"Hello! Can I make a suggestion to help improve this wonderful app? It would be interesting to introduce a function that tells you when you have completed the sets and repetitions that you have set for an exercise (for example: green color for completed set, red color for incomplete set). What do you think?" Thanks

[rolandgeider]

Moving this to the flutter repo, since this would be only for the mobile app