feat(demo): Replace account_child with account_circle
feat(demo): Replace account_child with account_circle

account_child has been removed from the Material icon collection

- Closes #314

papyros/qml-material,papyros/qml-material,ricardomv/qml-material,papyros/qml-material,jneidlinger/qml-material,osechet/qml-material,ricardomv/qml-material,jneidlinger/qml-material,hunt978/qml-material,hunt978/qml-material,benevo-qml/qml-material,jneidlinger/qml-material,hunt978/qml-material,papyros/qml-material,ricardomv/qml-material,jneidlinger/qml-material,benevo-qml/qml-material,osechet/qml-material,ricardomv/qml-material,benevo-qml/qml-material,benevo-qml/qml-material,osechet/qml-material,osechet/qml-material,hunt978/qml-material