Implement cc:insertPassthroughAttributes

see: https://stackoverflow.com/questions/49570803/is-is-possible-to-pass-passthrough-attributes-in-a-custom-composite-component/49597778?noredirect=1#comment86203170_49597778

Start by reading the linked Stack Overflow discussion to understand the requested cc:insertPassthroughAttributes behavior, then locate the relevant Jakarta Faces component implementation and tests. Done means the behavior is implemented and covered by tests, but this issue names no files or test entry points, so the component area must first be identified.

Written by the indexing model from the issue text.