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/Backlinks.tsx

@@ -2,11 +2,11 @@ import { QuartzComponentConstructor, QuartzComponentProps } from "./types"
 import style from "./styles/backlinks.scss"
 import { resolveRelative, simplifySlug } from "../util/path"
 
-function Backlinks({ fileData, allFiles }: QuartzComponentProps) {
+function Backlinks({ fileData, allFiles, displayClass }: QuartzComponentProps) {
   const slug = simplifySlug(fileData.slug!)
   const backlinkFiles = allFiles.filter((file) => file.links?.includes(slug))
   return (
-    <div class="backlinks">
+    <div class={`backlinks ${displayClass ?? ""}`}>
       <h3>Backlinks</h3>
       <ul class="overflow">
         {backlinkFiles.length > 0 ? (