[fix] Show hidden dirs and files in Choose screensaver image (#4121)
[fix] Show hidden dirs and files in Choose screensaver image (#4121)

Fixes #4117.
houqp/koreader,NiLuJe/koreader,NiLuJe/koreader,mihailim/koreader,Frenzie/koreader,poire-z/koreader,Markismus/koreader,koreader/koreader,pazos/koreader,koreader/koreader,Hzj-jie/koreader,mwoz123/koreader,Frenzie/koreader,poire-z/koreader