FilterButton adds filter in arbitrary order

Nobody has claimed this yet.

**What you were expecting:**

Adding a new filter using the FilterButton shows the filter at the end of the current filter list

**What happened instead:**

The new filter appears at an arbitrary position

**Steps to reproduce:**

1. Open the e-commerce demo https://marmelab.com/react-admin-demo/#/
2. Click on the Orders menu
3. Add the "Min amount" filter
4. Add the "customer" filter
5. The Customer filter appears in the middle instead of the end of the form

https://github.com/marmelab/react-admin/assets/99944/214b01e2-7ff3-45d2-a462-773717fbd32c

**Related code:**

This comes from the fact that the `displayedFilters` uses an object instead of an array:

https://github.com/marmelab/react-admin/blob/4089ad726b9ae699173790a6f97685a22426e34a/packages/ra-core/src/controller/list/queryReducer.ts#L95-L120

Why is it an object? This choice was made 7 years ago, when first implementing this feature:

https://github.com/marmelab/react-admin/commit/2e2604d0d93a420dc61e1b30d5f6dada501e4f12

**Possible Solution**

Store displayed filters as an array instead. But this breaks backwards compatibility for those with existing filters in localStorage, so the change must allow the code to work with an old data structure.

**Environment**

* React-admin version: all
* Last version that did not exhibit the issue (if applicable): none

Start in packages/ra-core/src/controller/list/queryReducer.ts, then trace the FilterButton displayedFilters flow and existing localStorage handling. Reproduce the Orders scenario in the e-commerce demo; done when newly added filters retain insertion order while existing object-shaped persisted filters continue to work.

Written by the indexing model from the issue text.