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/Breadcrumbs.tsx

@@ -58,7 +58,7 @@ export default ((opts?: Partial<BreadcrumbOptions>) => {
   // Merge options with defaults
   const options: BreadcrumbOptions = { ...defaultOptions, ...opts }
 
-  function Breadcrumbs({ fileData, allFiles }: QuartzComponentProps) {
+  function Breadcrumbs({ fileData, allFiles, displayClass }: QuartzComponentProps) {
     // Hide crumbs on root if enabled
     if (options.hideOnRoot && fileData.slug === "index") {
       return <></>
@@ -103,7 +103,7 @@ export default ((opts?: Partial<BreadcrumbOptions>) => {
       }
     }
     return (
-      <nav class="breadcrumb-container" aria-label="breadcrumbs">
+      <nav class={`breadcrumb-container ${displayClass ?? ""}`} aria-label="breadcrumbs">
         {crumbs.map((crumb, index) => (
           <div class="breadcrumb-element">
             <a href={crumb.path}>{crumb.displayName}</a>