fix: Fix Backlinks not applying the display class (#519)

* fix: Fix `Backlinks` not applying the display class

Fix #518

* fix: Apply `displayClass` to all layout components

* refactor: Use same style

* fix: Remove `undefined` class using coalescing operator

quartz/components/Search.tsx

@@ -1,12 +1,12 @@
-import { QuartzComponentConstructor } from "./types"
+import { QuartzComponentConstructor, QuartzComponentProps } from "./types"
 import style from "./styles/search.scss"
 // @ts-ignore
 import script from "./scripts/search.inline"
 
 export default (() => {
-  function Search() {
+  function Search({ displayClass }: QuartzComponentProps) {
     return (
-      <div class="search">
+      <div class={`search ${displayClass ?? ""}`}>
         <div id="search-icon">
           <p>Search</p>
           <div></div>