Better notebook markup renderer api (#121882)

* 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

extensions/notebook-markdown-extensions/notebook/tsconfig.json

@@ -3,6 +3,7 @@
 	"compilerOptions": {
 		"outDir": "./dist/",
 		"jsx": "react",
+		"module": "es2020",
 		"lib": [
 			"es2018",
 			"DOM",