Decide which top bar to hide

[MuntashirAkon]

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 Add Libraries #277) in the navigation bar. This way, user can distinguish between windows.