UX: Add theme settings and value transformers (#67)

This commit adds the above for these core site
settings:

* search_experience
* enable_welcome_banner

Since for horizon we want better control of
the default experience of these settings OOTB.

See also https://github.com/discourse/discourse/pull/31917

javascripts/discourse/api-initializers/horizon.gjs

@@ -1,8 +1,18 @@
 import { apiInitializer } from "discourse/lib/api";
 import CustomColorHtmlClass from "../components/custom-color-html-class";
+import CustomUserPalette from "../components/custom-user-palette";
 import ExperimentalScreen from "../components/experimental-screen";
 
 export default apiInitializer("1.8.0", (api) => {
   api.renderInOutlet("above-main-container", ExperimentalScreen);
   api.renderInOutlet("above-main-container", CustomColorHtmlClass);
+  api.renderInOutlet("sidebar-footer-actions", CustomUserPalette);
+
+  api.registerValueTransformer("site-setting-enable-welcome-banner", () => {
+    return settings.enable_welcome_banner;
+  });
+
+  api.registerValueTransformer("site-setting-search-experience", () => {
+    return settings.search_experience;
+  });
 });

javascripts/discourse/api-initializers/user-pallette.js

@@ -1,6 +0,0 @@
-import { apiInitializer } from "discourse/lib/api";
-import CustomUserPalette from "../components/custom-user-palette";
-
-export default apiInitializer("1.8.0", (api) => {
-  api.renderInOutlet("sidebar-footer-actions", CustomUserPalette);
-});