* Better notebook markup renderer api
For #121256
- Use js modules for notebook output renderers
- Rename apis from `markdown` to `markup`
- Use imports and exports for apis instead of globals for apis
- Use esbuild instead of webpack so we can emit js modules
- Clearly split top level markup renderes from renderers that extend other renderers
* Use constant instead of comment for replacement
Matt Bierner
4cb27d2ec7