build: use static CSS and JS filenames in dev (#534)

In production, it's helpful to use content addressing to guarantee cache busting
when publishing changes.

However, in development, because the server serves a static copy of the
index.html, that means that changing the Javascript bundle or CSS requires an
otherwise-unnecessary restart of the server.

This change makes the CSS and JS assets use fixed filenames so that a server
restart isn't needed.

Downside of this approach is there's now a dev/prod disparity and the config is
more spread out between files. The positive is we don't need to modify the
semantics of the server at all.

amundsen_application/static/webpack.common.ts

@@ -100,11 +100,7 @@ const config: webpack.Configuration = {
   plugins: [
     new CleanWebpackPlugin(),
     new MomentLocalesPlugin(), // To strip all locales except “en”
-    new MiniCssExtractPlugin({
-      filename: '[name].[contenthash].css',
-    }),
     ...htmlWebpackPluginConfig,
-    // new BundleAnalyzerPlugin(),   // Uncomment to analyze the production bundle on local
   ],
   optimization: {
     moduleIds: 'hashed',

amundsen_application/static/webpack.dev.ts

 import merge from 'webpack-merge';
+import MiniCssExtractPlugin from 'mini-css-extract-plugin';
 // import { BundleAnalyzerPlugin } from 'webpack-bundle-analyzer';
 
 import commonConfig from './webpack.common';
@@ -7,6 +8,12 @@ export default merge(commonConfig, {
   mode: 'development',
   devtool: 'inline-source-map',
   plugins: [
+    new MiniCssExtractPlugin({
+      filename: '[name].dev.css',
+    }),
     // new BundleAnalyzerPlugin()     // Uncomment to check the bundle size on dev
   ],
+  output: {
+    filename: '[name].dev.js',
+  },
 });

amundsen_application/static/webpack.prod.ts

+import MiniCssExtractPlugin from 'mini-css-extract-plugin';
 import merge from 'webpack-merge';
 import TerserPlugin from 'terser-webpack-plugin';
 import commonConfig from './webpack.common';
@@ -14,4 +15,9 @@ export default merge(commonConfig, {
       }),
     ],
   },
+  plugins: [
+    new MiniCssExtractPlugin({
+      filename: '[name].[contenthash].css',
+    }),
+  ],
 });