Sort folders and files by name "en block"

[exalate-issue-sync]

Userstory

As a user who sorts items by name in the fileslist I want that folders always show up "en-block" and files as well so that I can browse filelists quicker with my eyes.

Acceptance Criterias

Same behavior as in oc10

• affects only sorting by name
• En-Block: Ascending order (a-z): Folders first, then files
• En-Block: Descending order (z-a): Files first, then folders second
• Sorting by "modified date" or "size" is not affected by this en block sorting