Refactored app service providers

Removed old pagination provider as url handling now achieved in a better
way.
Removed unused broadcast service provider.
Moved view-based tweaks into specific provider.
Reorganised provider config list.

app/Providers/ValidationRuleServiceProvider.php

@@ -0,0 +1,30 @@
+<?php
+
+namespace BookStack\Providers;
+
+use BookStack\Uploads\ImageService;
+use Illuminate\Support\Facades\Validator;
+use Illuminate\Support\ServiceProvider;
+
+class ValidationRuleServiceProvider extends ServiceProvider
+{
+    /**
+     * Register our custom validation rules when the application boots.
+     */
+    public function boot(): void
+    {
+        Validator::extend('image_extension', function ($attribute, $value, $parameters, $validator) {
+            $extension = strtolower($value->getClientOriginalExtension());
+
+            return ImageService::isExtensionSupported($extension);
+        });
+
+        Validator::extend('safe_url', function ($attribute, $value, $parameters, $validator) {
+            $cleanLinkName = strtolower(trim($value));
+            $isJs = strpos($cleanLinkName, 'javascript:') === 0;
+            $isData = strpos($cleanLinkName, 'data:') === 0;
+
+            return !$isJs && !$isData;
+        });
+    }
+}