Rich workspaces: Collapse empty space

### Is your feature request related to a problem? Please describe.
The app shows a huge empty space at the top of the root files/folders list if one has "rich workspace" enabled and a readme.md file with a single character in it. The preview of the readme.md files uses one line, the other round about 8 lines are just empty, wasted space.

### Describe the solution you'd like
First of all am not sure it's a good idea to assume that just because the rich workspace is enabled for the webui it should also be enabled for the app UI. The webui tends to have a lot more space available then the app UI on a mobile device. So there should be at least a setting to enable/disable linking the rich workspace setting to the app.

Further, even if the rich workspace is enabled for the app, it should not waste any space, i.e. not cause any empty space in the UI. Hence, if the preview of the readme.md needs one line, it should only use one line.