Extends the functionality for the vfs.file.exists Agent item.
vfs.file.exists[file,<type>,<mode>,<user>,<group>]
type:
- file (default)
 - any
 - dir(ectory)
 - link
 - pipe
 - socket
 - block (device)
 - char (device)
 
mode:
 UNIX Octal representation of the File Permissions including setuid,setgid,sticky bit
user:
 username according to passwd
group:
 groupname according to group
All of this should be POSIX compatible, Windows includes file,any and dir type only.
This patch basically implements ZBXNEXT-1867 and ZBXNEXT-2921
- duplicates
 - 
                    
ZBXNEXT-2921 Extend vfs.file.exists capabilities to test file properties
-         
 - Closed
 
 -         
 - 
                    
ZBXNEXT-1867 Support more file types by vfs.file.exists
-         
 - Closed
 
 -         
 
- is duplicated by
 - 
                    
ZBXNEXT-3369 vfs.file.exists[file,<mode>]
-         
 - Closed
 
 -