Add possibility to navigate in folder hierarchy

### Actual behaviour
Navigating in deep folder structures is a bit frustrating, because I keep clicking the "back" (arrow) button. Clickling one of the navigation element in the left swipe menu sends me strictly to the root dir and is not really a help to reach folders in between.

### Expected behaviour
The current folder title is a button. When I click the button, it shows me the folder path / structure as a list representing the folder hierarchie. Alternatively longpressing the backbutton is fine too, but the folder title as button would be faster in usability.

### Steps to reproduce
1. Create a deep folder structure on server
2. Navigate to the last element in the hierarchie
3. Try to navigate back to a folder of choice

### Environment data
Android version: 7.1.2

Device model: BQ X5P

Stock or customized system: LineageOS

Nextcloud app version: 3.1.0

Nextcloud server version: 13.0.2

### Logs
#### Web server error log
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#### Nextcloud log (data/nextcloud.log)
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