feat: added tests for the fix on the SiteURIFactory

- I wrote some tests for the fixes I made to the SiteURIFactory
- I reverted the retrieval of the config from the App class within SiteURIFactory, the reason is explained in the pull request: https://github.com/codeigniter4/CodeIgniter4/pull/9607/files/f60db2cf341e98d4cc3250d8eb0fbefab2cf660f#diff-2bdcab9f3781f203b6582279dec4886d261349628487f14baed6e8b53f3e772e

Author: Franky5831

system/HTTP/SiteURIFactory.php

@@ -111,7 +111,7 @@ public function detectRoutePath(string $protocol = ''): string
      */
     private function parseRequestURI(): string
     {
-        $appConfig = $this->appConfig;
+        $appConfig = config(App::class);
         $baseUrl   = $appConfig->baseURL;
         $indexPage = $appConfig->indexPage;
         $baseUri   = false;

tests/system/HTTP/SiteURIFactoryTest.php

@@ -171,4 +171,44 @@ public static function provideCreateFromStringWithoutIndexPage(): iterable
             ],
         ];
     }
+
+    public function testCreateFromStringWithIndexPageSubDirCombinations(){
+        $standardUrl = "http://localhost:8080";
+        $subDirectoryAppsOptions = array(
+            array(
+                "subDir" => "",
+                "indexPage" => ""
+            ),
+            array(
+                "subDir" => "",
+                "indexPage" => "index.php"
+            ),
+            array(
+                "subDir" => "/subdir",
+                "indexPage" => ""
+            ),
+            array(
+                "subDir" => "/subdir",
+                "indexPage" => "index.php"
+            ),
+            array(
+                "subDir" => "/subdir/subsubdir",
+                "indexPage" => "index.php"
+            ),
+        );
+        foreach($subDirectoryAppsOptions as $option){
+            $route = "woot";
+            config(App::class)->baseURL = $standardUrl . $option["subDir"];
+            config(App::class)->indexPage = $option["indexPage"];
+            
+            $_SERVER['PATH_INFO']    = '/' . $route;
+            $_SERVER['REQUEST_URI']  = $option["subDir"] . "/" . $option["indexPage"] . $_SERVER['PATH_INFO'];
+            $_SERVER['SCRIPT_NAME']  = $option["subDir"] . "/" .$option["indexPage"];
+            $_SERVER['HTTP_HOST']    = $standardUrl;
+
+            $factory = $this->createSiteURIFactory();
+            $detectedRoutePath = $factory->detectRoutePath();
+            $this->assertSame($route, $detectedRoutePath);
+        }
+    }
 }