ls: Implement the '-a' (all) flag
ls: Implement the '-a' (all) flag

The all flag did not cull/remove the directory entries starting with a
dot. The help message indicates it should. The implementation checks
if the string starts with a dot whilst also using '-a' to determine
whether a DirEntry is to be printed.

jbcrail/coreutils,uutils/coreutils,Arcterus/coreutils,wimh/coreutils,kevgeniy/coreutils,keunwoo/coreutils,keunwoo/coreutils,tempbottle/coreutils,kevgeniy/coreutils,Heather/coreutils,jbcrail/coreutils,wimh/coreutils,ebfe/coreutils,ebfe/coreutils,uutils/coreutils,Arcterus/coreutils,uutils/coreutils,tempbottle/coreutils,Heather/coreutils