Improve EmbeddedEditor and EmbeddedView usage experience

The EmbeddedEditor and EmbeddedViewer classes are convenience React components to abstract the creation of an Editor that runs inside its Envelope on an <iframe>. The EmbeddedEditor exposes a Ref object that allows other components to imperatively call methods.

The EmbeddedEditor reference object should implement the Editor interface, since it should provide the exact same features that an Editor does.

The EmbeddedEditor props object already accepts that override the implementation of `KogitoChannelApi`, therefore, the Props object should expose the portion of `KogitoChannelApi` that can be overridden by components using EmbeddedEditor. The same applies to EmbeddedViewer.

This task is to actually make that change and improve the EmbeddedEditor and EmbeddedViewer usage experiences.