DEV: port full-width component to be included directly (#126)

Removes the [full-width
component](https://github.com/discourse/discourse-full-width-component)
dependency by adding most of the code directly to the theme. There was
one grid definition in the CSS I ended up removing because it was
conflicting with an existing override in the theme.

Anyone who has previously installed the theme should manually remove the
full-width component from it.

javascripts/discourse/api-initializers/full-width-logo-behavior.js

@@ -0,0 +1,16 @@
+import { apiInitializer } from "discourse/lib/api";
+
+export default apiInitializer("0.8", (api) => {
+  document.body.classList.add("full-width-enabled");
+
+  // When the sidebar is visible, force the HomeLogo to be in an 'un-minimized' state.
+  api.registerValueTransformer?.(
+    "home-logo-minimized",
+    ({ value, context }) => {
+      if (value && context.showSidebar) {
+        return false;
+      }
+      return value;
+    }
+  );
+});