Add license headers to source files

cypress/e2e/1-demo/demo.cy.ts

src/main.ts

src/observables/MessageFromParent.ts

src/parent/common.ts

src/parent/iframe.ts

src/parent/load.ts

src/parent/parent.ts

src/random.ts

src/types/IChatterboxConfig.ts

src/ui/views/AccountSetupView.ts

src/ui/views/ChatterboxView.ts

src/ui/views/FooterView.ts

src/ui/views/LoadingView.ts

src/ui/views/RootView.ts

src/viewmodels/AccountSetupViewModel.ts

src/viewmodels/ChatterboxViewModel.ts

src/viewmodels/FooterViewModel.ts

src/viewmodels/RootViewModel.ts

src/viewmodels/tiles.ts