Theme System: Fixed theme view before/after issues

- Updated the system to work with modules.
- Updated module docs to consider namespacing.
- Fixed view loading and registration event ordering.
- Fixed checking if views are registered.

tests/Theme/ThemeModuleTest.php

@@ -5,7 +5,7 @@ namespace Tests\Theme;
 use BookStack\Facades\Theme;
 use Tests\TestCase;
 
-class ThemeModuleTests extends TestCase
+class ThemeModuleTest extends TestCase
 {
     public function test_modules_loaded_on_theme_load()
     {
@@ -207,6 +207,19 @@ class ThemeModuleTests extends TestCase
         });
     }
 
+    public function test_module_can_use_theme_view_render_functions()
+    {
+        $this->usingModuleFolder(function (string $moduleFolderPath) {
+            file_put_contents($moduleFolderPath . '/functions.php', "<?php\n\BookStack\Facades\Theme::listen(\BookStack\Theming\ThemeEvents::THEME_REGISTER_VIEWS, fn(\$views) => \$views->renderBefore('layouts.parts.header', 'cat', 100));");
+            mkdir($moduleFolderPath . '/views', 0777, true);
+            file_put_contents($moduleFolderPath . '/views/cat.blade.php', 'mysupercatispouncy');
+
+            $this->refreshApplication();
+
+            $this->asAdmin()->get('/')->assertSee('mysupercatispouncy');
+        });
+    }
+
     protected function usingModuleFolder(callable $callback): void
     {
         $this->usingThemeFolder(function (string $themeFolder) use ($callback) {