Feature Request: Allow user-specified format for Photos subfolders on iOS App

When using the iOS app and uploading photos to Nextcloud, there is only an option to toggle "Use Subfolders" with a default subfolder format of /year/month rather than allowing the user to select the folder structure desired. The app should allow for the user to specify the folder structure (e.g. /year-month-date or /year/month-date). There was a comment to this effect on the Nextcloud forum in April 2020.

There is no workaround to this issue within Nextcloud, although it is possible to use the PhotoSync app to achieve a user-selected folder structure for uploads to Nextcloud using the WebDAV interface. The problem is that this app imposes additional costs on users for full resolution uploads. It would be optimal to eliminate this limitation in the Nextcloud app by implementing this feature natively within the app itself.

Steps to reproduce

1. Go to Auto upload on iOS app
2. Scroll to Use Subfolders. There is only an option to toggle but not select format

Expected behaviour

There should be an option for the user to select directory format

Actual behaviour

A default subfolder format of /year/month is selected with no user choice

Screenshots

If applicable, add a screenshot showing the issue.

Logs

If applicable, you can post the iOS app or server logs (removing any sensitive information).

Reasoning or why should it be changed/implemented?

Environment data

**iOS version: 14.8

**Nextcloud iOS app version: 4.0.6

**Server operating system: Ubuntu Server 20.04

**Web server: Apache

**Database: SQLite

PHP version:

**Nextcloud version: 22.1.1

Start at the iOS app's Auto upload screen, especially the Use Subfolders setting, and trace how its current /year/month choice is applied during photo uploads. Determine how users should select a folder format, then verify uploads create the selected structure rather than the default; the issue names no files or tests, so locating those entry points is part of the work.