Remove dropdown sort bar and add root info header

In docsUI new design, dropdown sort bar will not exist anymore.
User only can sort file by overflow menu sort item on phone.
It will have table header sort bar on tablet in list mode.
In addition, it needs to show root info on top of directory,
add a new label to handle this text info.
1. Remove DropdownSortWidgetController and refactor.
2. Refactor test to use overflow menu to sort.
3. Remove some tests because some values are removed.
4. Add header title on directory_header.
5. Set gravity center_vertical on bread crumb title.

Bug: 120467268
Bug: 120260716
Fix: 120634552
Test: atest DocumentsUITests
Change-Id: I23703cd94f171e90a352809880e189bb7e1e3741