chore: Suppress Unused CSS selector warnings.

We should, obviously, rather just clean up the CSS. But for now, the
warnings are spamming the console to the point where actual debugging is
impossible: debug statements and logging is drowned in this noise.

From sveltejs/svelte-loader#67

webpack.config.js

@@ -52,6 +52,9 @@ module.exports = {
                         preprocess: require("svelte-preprocess")({
                             paths: ["src", "src/stylesheets"],
                         }),
+                        onwarn(warning, onwarn) { // Disable "Unused CSS Selector" warnings. We should clean out the CSS instead.
+                          return warning.code === 'css-unused-selector' || onwarn(warning);
+                        },
                     },
                 },
             },