Added inbound references listing for pages

app/Http/Controllers/ReferenceController.php

@@ -0,0 +1,47 @@
+<?php
+
+namespace BookStack\Http\Controllers;
+
+use BookStack\Auth\Permissions\PermissionApplicator;
+use BookStack\Entities\Models\Page;
+use Illuminate\Database\Eloquent\Relations\Relation;
+
+class ReferenceController extends Controller
+{
+
+    protected PermissionApplicator $permissions;
+
+    public function __construct(PermissionApplicator $permissions)
+    {
+        $this->permissions = $permissions;
+    }
+
+    /**
+     * Display the references to a given page.
+     */
+    public function page(string $bookSlug, string $pageSlug)
+    {
+        /** @var Page $page */
+        $page = Page::visible()->whereSlugs($bookSlug, $pageSlug)->firstOrFail();
+
+        $baseQuery = $page->referencesTo()
+            ->where('from_type', '=', (new Page())->getMorphClass())
+            ->with([
+                'from' => fn(Relation $query) => $query->select(Page::$listAttributes),
+                'from.book' => fn(Relation $query) => $query->scopes('visible'),
+                'from.chapter' => fn(Relation $query) => $query->scopes('visible')
+            ]);
+
+        $references = $this->permissions->restrictEntityRelationQuery(
+            $baseQuery,
+            'references',
+            'from_id',
+            'from_type'
+        )->get();
+
+        return view('pages.references', [
+            'page' => $page,
+            'references' => $references,
+        ]);
+    }
+}