Fixup all RuboCop warnings.

Library/Homebrew/brew.rb

Library/Homebrew/cask/lib/hbc/artifact/base.rb

Library/Homebrew/cask/lib/hbc/artifact/uninstall_base.rb

Library/Homebrew/cask/lib/hbc/cask.rb

Library/Homebrew/cask/lib/hbc/cask_loader.rb

Library/Homebrew/cask/lib/hbc/cli.rb

Library/Homebrew/cask/lib/hbc/cli/abstract_command.rb

Library/Homebrew/cask/lib/hbc/cli/doctor.rb

Library/Homebrew/cask/lib/hbc/cli/info.rb

Library/Homebrew/cask/lib/hbc/cli/install.rb

.../Homebrew/cask/lib/hbc/cli/internal_appcast_checkpoint.rb

Library/Homebrew/cask/lib/hbc/cli/list.rb

Library/Homebrew/cask/lib/hbc/container/dmg.rb

Library/Homebrew/cask/lib/hbc/download_strategy.rb

Library/Homebrew/cask/lib/hbc/dsl.rb

Library/Homebrew/cask/lib/hbc/exceptions.rb

Library/Homebrew/cask/lib/hbc/system_command.rb

Library/Homebrew/cmd/deps.rb

Library/Homebrew/cmd/help.rb

Library/Homebrew/cmd/link.rb