Apply Clang-tidy (#918)

.clang-tidy

examples/component/homescreen.cpp

include/ftxui/screen/pixel.hpp

src/ftxui/component/button.cpp

src/ftxui/component/collapsible.cpp

src/ftxui/component/component.cpp

src/ftxui/component/component_options.cpp

src/ftxui/component/dropdown.cpp

src/ftxui/component/event.cpp

src/ftxui/component/hoverable.cpp

src/ftxui/component/hoverable_test.cpp

src/ftxui/component/input.cpp

src/ftxui/component/menu.cpp

src/ftxui/component/radiobox.cpp

src/ftxui/component/screen_interactive.cpp

src/ftxui/component/terminal_input_parser.cpp

src/ftxui/component/window.cpp

src/ftxui/dom/benchmark_test.cpp

src/ftxui/dom/border.cpp

src/ftxui/dom/box_helper.cpp