Add SelectTextOnFocusBehavior to automatically select the content of a TextBox when it is focused.#836

vgromfeld wants to merge 3 commits intoCommunityToolkit:mainCommunityToolkit/Windows:mainfrom

vgromfeld:selectTextOnFocusBehaviorvgromfeld/CommunityToolkit.Windows:selectTextOnFocusBehaviorCopy head branch name to clipboard