housekeeping: bundle size reductions (#4713)

* set new bundlesize goal
* preserve `GeneratorFunction` instead of all function names
* use js-yaml fork that doesn't require esprima
* set HTML content directly, instead of using React-Markdown
* use remarkable for all Markdown rendering
* add babel-plugin-transform-react-remove-prop-types
* remove SplitPaneMode plugin
* remove react-collapse
* remove AST plugin, and yaml-js
* trim Markdown HTML string output before rendering
* disable obsolete function name preservation
* add `getComponent` to propTypes

src/core/plugins/configs/helpers.js

@@ -1,4 +1,4 @@
-import YAML from "js-yaml"
+import YAML from "@kyleshockey/js-yaml"
 
 export const parseYamlConfig = (yaml, system) => {
   try {