Theme: support style arrays on all components

[jsonxr]

Currently only a singluar style is supported.

Change to:

export interface Props {
  style?: TextStyle | TextStyle[]
}

export Component = ({style, ...props}) => {
  // ...
  let textStyle: TextStyle[] = [];
  if (style) {
    if (Array.isArray(style)) {
      textStyle = textStyle.concat(style);
    } else {
      textStyle.push(style);
    }
  }
}