unlock with PIN (#8977)

* add custom password to unlock settings

* If not set, use admin password; if set, use custom settings password.
* At least 4 characters.
* Set with gui or command line.

Signed-off-by: 21pages <sunboeasy@gmail.com>

* Update cn.rs

---------

Signed-off-by: 21pages <sunboeasy@gmail.com>
Co-authored-by: RustDesk <71636191+rustdesk@users.noreply.github.com>

src/lang/ca.rs

@@ -632,5 +632,9 @@ pub static ref T: std::collections::HashMap<&'static str, &'static str> =
         ("About RustDesk", ""),
         ("Send clipboard keystrokes", ""),
         ("network_error_tip", ""),
+        ("Unlock with PIN", ""),
+        ("Requires at least {} characters", ""),
+        ("Wrong PIN", ""),
+        ("Set PIN", ""),
     ].iter().cloned().collect();
 }