Code blocks in tinymce could sometimes end up exploded into the sub
elements of the codemirror display.
This changes the strategy to render codemirror within the shadow dom of
a custom element while preserving the normal pre/code DOM structure.
Still a little instability when moving/adding code blocks within details
blocks but much harder to break things now.
- Split everything into specific plugin/concern files to make things
more managable. Means original component file is now simple and much
of the core config is focused in one place.
