implement red dot support for UIBarButtonItem#1974

kumarmohit5189 wants to merge 3 commits intomicrosoft:mainmicrosoft/fluentui-apple:mainfrom

kumarmohit5189:kumarmohit/red_dot_bar_buttonkumarmohit5189/fluentui-apple:kumarmohit/red_dot_bar_buttonCopy head branch name to clipboard