feat(build): webpack@5 and webpack-dev-server@4 (#7826)

SwaggerUI is now built using `webpack@5`, with dev support for `webpack-dev-server@4`
- ES Module output bundle path now points to `swagger-ui-es-bundle-core`, which does not include dependencies
- No change to CommonJS output bundle or path
- Now uses Asset Modules, which replaces `file-loader`, `raw-loader`, and `url-loader`
- Removed unused rules/loaders for `.woff | .woff2 | .ttf | .eot` fonts and html
- Node polyfills are no longer bundled with `webpack@5`, and must be loaded separately and/or use `resolve.fallback`. 
As an example, SwaggerUI loads `process`, `buffer`, and `stream-browserify` as `devDependencies` in order to build development and production bundles.

SwaggerUI-React
- Now imports `swagger-ui-es-bundle-core`, and similarly outputs `swagger-ui-es-bundle-core` to its `dist` directory

Dev notes:
- Order of execution matters for the production npm build scripts. `build-stylesheets` needs to get built first, 
then cleanup of any empty artifacts, before building the various production bundles
- `Dev-helpers` now relies on `HTMLWebpackPlugin` to inject css and bundle files

webpack/stylesheets.babel.js

@@ -7,7 +7,6 @@
 
 import path from "path"
 import MiniCssExtractPlugin from "mini-css-extract-plugin"
-import IgnoreAssetsPlugin from "ignore-assets-webpack-plugin"
 
 export default {
   mode: "production",
@@ -60,11 +59,6 @@ export default {
     new MiniCssExtractPlugin({
       filename: "[name].css",
     }),
-    new IgnoreAssetsPlugin({
-      // This is a hack to avoid a Webpack/MiniCssExtractPlugin bug, for more
-      // info see https://github.com/webpack-contrib/mini-css-extract-plugin/issues/151
-      ignore: ["swagger-ui.js", "swagger-ui.js.map"],
-    }),
   ],
 
   devtool: "source-map",