minor #43612 [BrowserKit][HttpClient][Routing] support building query strings with stringables (nicolas-grekas, OskarStark)

This PR was merged into the 5.4 branch.

Discussion
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[BrowserKit][HttpClient][Routing] support building query strings with stringables

| Q             | A
| ------------- | ---
| Branch?       | 5.4
| Bug fix?      | no
| New feature?  | yes (minor)
| Deprecations? | no
| Tickets       | Fix #26992
| License       | MIT
| Doc PR        | -

Allows using eg an instance of `Uid` as a route parameter.

Replaces #42057

Commits
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65e2caca30 Add check and tests for public properties
ab38bb8b6c [BrowserKit][HttpClient][Routing] support building query strings with stringables

Author: Tobion

Impersonate/ImpersonateUrlGenerator.php

@@ -69,7 +69,7 @@ private function buildExitPath(string $targetUri = null): string
             $targetUri = $request->getRequestUri();
         }
 
-        $targetUri .= (parse_url($targetUri, \PHP_URL_QUERY) ? '&' : '?').http_build_query([$switchUserConfig['parameter'] => SwitchUserListener::EXIT_VALUE]);
+        $targetUri .= (parse_url($targetUri, \PHP_URL_QUERY) ? '&' : '?').http_build_query([$switchUserConfig['parameter'] => SwitchUserListener::EXIT_VALUE], '', '&');
 
         return $targetUri;
     }