Decide which top bar to hide

Currently, the currently accessed directory bar is shown and the top navigation bar is hidden, which has aesthetic and design issues:

1. To search or change view mode or access the side menu (you cannot access Menu by swiping right if you enabled gesture navigation in Android 10), you have to swipe down (which makes the navigation bar visible) which is not convenient.
2. When you select multiple files and/or folders, the navigation bar has to appear as it is used for selection.

Conclusion:

1. Hide currently accessed directory bar instead of the top navigation bar. This way, you will not need to make it visible when selecting multiple files and/or folders.
2. Show the name of the current directory only (or Library name if you ever going to implement #277) in the navigation bar. This way, user can distinguish between windows.

Start by reproducing the current directory bar and top navigation behavior in Android, including multi-file selection and gesture navigation on Android 10. Review the navigation UI entry points and compare the proposed bar visibility and current-directory labeling. Done means the chosen bar remains available for search, view mode, menus, and selection, while users can distinguish windows by the displayed directory or library name.