Android app: custom icons for folders

[ZMJGMADHPXWT]

Describe the feature you'd like to request

I'd like to be able to configure custom icons for every Floccus folder.

Describe the solution you'd like

It's a good idea to configure icon for every folder, it will help to navigate quicker.

Describe alternatives you've considered

[github-actions]

Hello 👋

Thank you for taking the time to open this issue with floccus. I know it's frustrating when software
causes problems. You have made the right choice to come here and open an issue to make sure your problem gets looked at
and if possible solved. Let me give you a short introduction on what to expect from this issue tracker to avoid misunderstandings.
I'm Marcel. I created floccus a few years ago, and have been maintaining it since. I currently work for Nextcloud
which leaves me with less time for side projects like this one than I used to have.
I still try to answer all issues and if possible fix all bugs here, but it sometimes takes a while until I get to it.
Until then, please be patient. It helps when you stick around to answer follow up questions I may have,
as very few bugs can be fixed directly from the first bug report, without any interaction. If information is missing in your bug report
and the issue cannot be solved without it, I will have to close the issue after a while.
Note also that GitHub in general is a place where people meet to make software better together. Nobody here is under any obligation
to help you, solve your problems or deliver on any expectations or demands you may have, but if enough people come together we can
collaborate to make this software better. For everyone.
Thus, if you can, you could also have a look at other issues to see whether you can help other people with your knowledge
and experience. If you have coding experience it would also be awesome if you could step up to dive into the code and
try to fix the odd bug yourself. Everyone will be thankful for extra helping hands!
If you cannot lend a helping hand, to continue the development and maintenance of this project in a sustainable way,
I ask that you donate to the project when opening an issue (or at least once your issue is solved), if you're not a donor already.
You can find donation options at https://floccus.org/donate/. Thank you!

One last word: If you feel, at any point, like you need to vent, this is not the place for it; you can go to the Nextcloud forum,
to twitter or somewhere else. But this is a technical issue tracker, so please make sure to
focus on the tech and keep your opinions to yourself.

Thank you for reading through this primer. I look forward to working with you on this issue!
Cheers 💙