Improve selection of backup folder UX (Contacts, Calendar)

[genodeftest]

Checklist

• [X] I made sure that there are no existing issues - open or closed - to which I could contribute my information.
• [X] I made sure that there are no existing discussions - open or closed - to which I could contribute my information.
• [X] I have read the FAQs inside the app (Menu -> About -> FAQs), in the README and my problem isn't listed.
• [X] I have taken the time to fill in all the required details. I understand that the bug report may get dismissed otherwise.
• [X] This issue contains only one feature request.
• [X] I optionally donated to support the Fossify mission.

Which apps should have this feature?

Calendar, Contacts

Feature description

Steps to reproduce:

1. Open Fossify Contacts or Fossify Calendar
2. Open the three-dots-menu
3. Open Settings
4. Check Enable automatic backups
5. In the Manage automatic backups dialog, click the path under Folder
6. Navigate to and select an existing folder (e.g. Internal > Backups > Contacts in my case)
7. Confirm folder selection by clicking OK
8. In the dialog Confirm folder access, confirm with OK
9. In the parent of the backup folder (Internal > Backups in my case), click Use this folder
10. When asked to allow contacts (or calendar) to access files in the folder, confirm with Allow

Video/screencast

Why do you want this feature?

Expected behavior

I expect to only select a single folder, as I'm only storing backups to a single folder. In other words, it would be nice to only have steps 6/7 OR 8/9/10. Also, in step 9, I expect to give Fossify Contacts/Calendar access only to the backup directory (Internal > Backups > Contacts in my case), not to its parent.

Actual behavior

I am asked for locations twice, first with a Fossify dialog, then with a system dialog. I have to give Fossify apps permissions to the backup directory's parent (Internal > Backups in my case).

Additional information

I'm not entirely sure whether this is a bug or a missing feature, so I've reported it as feature request. Please feel free to change it to bug if that is more suitable.

This is not a duplicate of FossifyOrg/Calendar#101. In contrast to that issue, I'm able to select the folder, I just need to do it twice (once with app's own dialog, once with system dialog).

A similar issue has been reported by @mpldr to SimpleMobileTools before (SimpleMobileTools/Simple-Contacts#1064):

The current DIY filepicker has some limitations, biggest of which is that you can't add existing locations. I keep my Backups in Internal/Backups/[App], which is synced via syncthing. This works quite well for everything except the most important stuff (contacts, calendars, notes).

Would it be possible to use the system file picker for choosing the location instead?

Affected app version

Fossify Calendar 1.0.2 (from GitHub release page or F-Droid, does not seem to matter) Fossify Contacts 1.0.1 (from GitHub release page or F-Droid, does not seem to matter)

Affected Android/Custom ROM version

Android 13, patchlevel 2024-01-05 (FP4.TP29.C.0101.20240121)

Affected device model

Fairphone 4

PS: This issue was originally reported as FossifyOrg/Commons#36

[mpldr]

I would prefer the 8-10 option, as this would also fix the storage scope issue on GrapheneOS

[genodeftest]

I think the 8-10 option is necessary for Android permissions anyways, even on the (almost) stock Android 13 of Fairphone 4.