Fix iOS id

iOS must use weighted predicates or it'll return the wrong result when multiple elements share the same id.

For example:
id('sign_in_label').click currently matches a static text and a button. The static text does nothing, so we'd prefer to return an element that has interactive abilities such as the button.

If someone wanted to match the static text using an id anyway, they could do s_text resolve_id 'sign_in_label'