Add a type for the "plain object" version of a class

[lukelafountaine]

It might be something like this:

type NonFunctionPropertyNames<T> = {
   [K in keyof T]: T[K] extends Function ? never : K;
}[keyof T];

export type PublicNonFunctionProperties<T> = Pick<T, NonFunctionPropertyNames<T>>;

[lukelafountaine]

cc @onebytegone