feature #34363 [HttpFoundation] Add InputBag (azjezz)

This PR was merged into the 5.1-dev branch.

Discussion
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[HttpFoundation] Add InputBag

| Q             | A
| ------------- | ---
| Branch?       | master
| Bug fix?      | no
| New feature?  | yes
| Deprecations? | yes
| License       | MIT

When ppl read a request attribute, they never check if an array is returned
This means many apps just fail with a 500 when adding `[]` in the query string.
This PR turns them to 400 basically (with a deprecation for now)

Commits
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0a2ef70c04 [HttpFoundation] add InputBag

Author: fabpot

Extension/HttpFoundation/HttpFoundationRequestHandler.php

@@ -63,7 +63,7 @@ public function handleRequest(FormInterface $form, $request = null)
                     return;
                 }
 
-                $data = $request->query->get($name);
+                $data = $request->query->all()[$name];
             }
         } else {
             // Mark the form with an error if the uploaded size was too large
@@ -87,7 +87,7 @@ public function handleRequest(FormInterface $form, $request = null)
                 $files = $request->files->all();
             } elseif ($request->request->has($name) || $request->files->has($name)) {
                 $default = $form->getConfig()->getCompound() ? [] : null;
-                $params = $request->request->get($name, $default);
+                $params = $request->request->all()[$name] ?? $default;
                 $files = $request->files->get($name, $default);
             } else {
                 // Don't submit the form if it is not present in the request