refactor windows specific session, file transfer and waiting for image (#7184)

* refactor windows specific session, file transfer and waiting for image

1. File transfer doesn't show directory until correct session id is ensured
2. Fix file transfer, caused by `pi.username = self.lc.read().unwrap().get_username(&pi);` in `handle_peer_info` override empty username and `get_active_username` doesn't return currect session username
* Fix home directory not change when session changed, or wrong home directory
* Fix show empty remote directory rather than error messagbox when current session is in login screen
3. Show `Connected, waiting for image` after user choose the same
   session id

Signed-off-by: 21pages <pages21@163.com>

* update translations

Signed-off-by: 21pages <pages21@163.com>

* Update connection.rs

---------

Signed-off-by: 21pages <pages21@163.com>
Co-authored-by: RustDesk <71636191+rustdesk@users.noreply.github.com>

src/flutter.rs

@@ -838,7 +838,7 @@ impl InvokeUiSession for FlutterHandler {
         self.push_event(
             "set_multiple_windows_session",
             vec![(
-                "user_sessions",
+                "windows_sessions",
                 &serde_json::ser::to_string(&msg_vec).unwrap_or("".to_owned()),
             )],
         );