Webpack 4 (WIP) (#12098)

* Webpack 4

* webpack: force angular version 1.6 as 1.7 has removed a legacy feature toggle Grafana needs, switched from awesome-typescript-loader to ts-loader & forked ts checker

* Webpack 4

* webpack: force angular version 1.6 as 1.7 has removed a legacy feature toggle Grafana needs, switched from awesome-typescript-loader to ts-loader & forked ts checker

* upgrade ts loader

* simplified splitChunks

* upgrade circle node image to v8

* webpack: minor changes, using the new mode option, removed unused awesome-typescript loader, investigating karma issue but no solution yet

* fix: change angular mocks version restriction to be more strict

* add babel-loader for HMR support, fix karma debug runner

* babel-loader to yarn.lock

* webpack: changed from ExtractTextPlugin  to MiniCssExtractPlugin, and updated the minification step to use new webpack4 optimization config section

* webpack: remove css minifcation from general css processing as it's done in the webpack optimization step

* limit vendors chunk to .ts and .js files

* fix: removed typescript compile error, wanted to see if we still got test failure for that

* tech: upgrade uglify-js, should be faster now

scripts/webpack/webpack.hot.js

@@ -42,20 +42,23 @@ module.exports = merge(common, {
       {
         test: /\.tsx?$/,
         exclude: /node_modules/,
-        use: {
-          loader: 'awesome-typescript-loader',
+        use: [{
+          loader: 'babel-loader',
           options: {
-            useCache: true,
-            useBabel: true,
-            babelOptions: {
-              babelrc: false,
-              plugins: [
-                'syntax-dynamic-import',
-                'react-hot-loader/babel'
-              ]
-            }
+            cacheDirectory: true,
+            babelrc: false,
+            plugins: [
+              'syntax-dynamic-import',
+              'react-hot-loader/babel'
+            ]
+          }
+        },
+        {
+          loader: 'ts-loader',
+          options: {
+            transpileOnly: true
           },
-        }
+        }],
       },
       {
         test: /\.scss$/,