[MM-59552] Remove unsafe-inline from internal CSP, replace with nonce and rework some dynamic styling (#3120)

* Remove unsafe-inline

* Fix dynamic dark mode loading

* Include nonce generator for CSP for styles

* Add nonce provider for react-select

* Fix test

webpack.config.renderer.js

@@ -152,7 +152,14 @@ module.exports = merge(base, {
             use: [
                 MiniCssExtractPlugin.loader,
                 'css-loader',
-                'sass-loader',
+                {
+                    loader: 'sass-loader',
+                    options: {
+                        sassOptions: {
+                            includePaths: [path.resolve(__dirname, 'node_modules')],
+                        },
+                    },
+                },
             ],
         }, {
             test: /\.mp3$/,