add onClicked parameter to HtmlText

[iankerr]

• adds new parameter to HtmlText composable to handle when non-linked text is clicked
• in example app:
  • adds Toasts to TextView and HtmlText to demonstrate new functionality
  • adds movementMethod to TextView clickable links work
  • removes layoutParams from TextView, as it doesn't seem to do anything
  • removes fillMaxWidth, from AndroidView containing TextView so that text doesn't take up entire width, to match the layout of the HtmlText