Add more diagnostics and manual interventions to the auto upload feature

### How to use GitHub

* Please use the 👍 [reaction](https://blog.github.com/2016-03-10-add-reactions-to-pull-requests-issues-and-comments/) to show that you are interested into the same feature.
* Please don't comment if you have no relevant information to add. It's just extra noise for everyone subscribed to this issue.
* Subscribe to receive notifications on status change and new comments.

**Is your feature request related to a problem? Please describe.**
It is Dec 30, and my Nextcloud app on Android sees none of the photos I've snapped since Dec 14.
I restarted the app. I rebooted the phone, I checked logs on the server. Nowhere do I see any clue or get any better result,
This is not the first time I've faced such behaviour and the lack of clear features for diagnosing such oddities and intervening manually is frustrating.

Under Settings > Sync > Auto upload, I can see my folders and play with some configs. And they are all fine and have worked for years. Nothing changes here. Just the app stops noticing new photos in the configured folders. Photos I can see here under Settings > Sync > Auto upload but are not on the Uploads log

**Describe the solution you'd like**
I'd particularly like to see improvements to the section Settings > Sync > Auto upload

It shows each configured folder with thumbnails and a cloud icon and an upright ellipsis menu at right.

1. I'd like on each thumbnail to see some indication of whether it was uploaded yet or not.
2. I'd like an item on the upright ellipsis menu that forces an upload of this folder now!
3. When I've forced that now, I'd like to have a status summary and to see the thumbnails of photos not uploaded and be able to tape the photo and find out why!

**Describe alternatives you've considered**
Memories app, but it doesn't upload. Will look into Les Pas. I consider sometimes cloning rhe repo, and setting up a dev environment to build this app and see if I work out how to add features like this.

**Additional context**
Only that I love Nextcloud and having a self hosted cloud server, but wish the android app had these features. It is simply nowhere near as reliable a Google Photos. Sadly.