[BUGFIX] JsonView creates array for ObjectStorage

The ObjectStorage internals return strings as keys for the elements,
when iterating over the storage.

Users expect JSON arrays (not objects) when rendering an ObjectStorage
through a JsonView.

The `toArray` method takes care of this key conversion.

Resolves: #66581
Releases: main
Change-Id: Ice2487f6e85e3949d9ee59174b6175c46b1ae8e1
Reviewed-on: https://review.typo3.org/c/Packages/TYPO3.CMS/+/77361


Tested-by: core-ci <typo3@b13.com>
Tested-by: Stefan Bürk <stefan@buerk.tech>
Tested-by: Christian Kuhn <lolli@schwarzbu.ch>
Reviewed-by: Simon Schaufelberger <simonschaufi+typo3@gmail.com>
Reviewed-by: Stefan Bürk <stefan@buerk.tech>
Reviewed-by: Oliver Klee <typo3-coding@oliverklee.de>
Reviewed-by: Christian Kuhn <lolli@schwarzbu.ch>
Reviewed-by: Georg Ringer <georg.ringer@gmail.com>