[BUGFIX] Keep parameters in link browser’s upload form

Any given attribute stored in the `P` parameter is kept and attached to
the return URL of the upload form.

Resolves: #83923
Releases: master, 8.7, 7.6
Change-Id: Id6ff93f0a30691f7bde84275128a34eb479499de
Reviewed-on: https://review.typo3.org/56592
Tested-by: TYPO3com <no-reply@typo3.com>
Reviewed-by: Steffen Kamper <info@sk-typo3.de>
Tested-by: Steffen Kamper <info@sk-typo3.de>
Reviewed-by: Daniel Goerz <ervaude@gmail.com>
Tested-by: Daniel Goerz <ervaude@gmail.com>
Reviewed-by: Markus Klein <markus.klein@typo3.org>
Tested-by: Markus Klein <markus.klein@typo3.org>

typo3/sysext/recordlist/Classes/Controller/AbstractLinkBrowserController.php

@@ -558,7 +558,8 @@ protected function getLinkAttributeFieldDefinitions()
     public function getUrlParameters(array $overrides = null)
     {
         return [
-            'act' => $overrides['act'] ?? $this->displayedLinkHandlerId
+            'act' => $overrides['act'] ?? $this->displayedLinkHandlerId,
+            'P' => $overrides['P'] ?? $this->parameters,
         ];
     }