Allow JavaScript components inside of props dict

Current Situation

Libraries like MaterialUI use components within the props dictionary, and this currently isn't supported by ReactPy.

Ref: https://github.com/reactive-python/reactpy/discussions/989#discussioncomment-5992719

Proposed Actions

We need to spend some additional thought on how to allow JavaScript components to be added as a prop value. This may result in adding some kind of internal flag that signifies "this prop value contains a component".