Ability to add a single React field to a plain ol' standard Rails form

[cmer]

I would like the ability to add just a single React field to an otherwise standard Rails form without having to change my entire form to use form_props. This would allow sprinkling some more advanced React components only when needed (ie: a more complex calendar picker).

Discussion at https://www.reddit.com/r/rails/comments/1i2wjth/comment/m7jvkqn/