Add Return 2 Games Launcher#742

MichaelHinrichs wants to merge 7 commits intoSteamDatabase:mainSteamDatabase/FileDetectionRuleSets:mainfrom

MichaelHinrichs:Return-2-Games-LauncherMichaelHinrichs/FileDetectionRuleSets:Return-2-Games-LauncherCopy head branch name to clipboard