Messenger receive file

• Add MessengerRegisterReceiveFileCallback function.
• Add MessengerStartFileTransfer function.
• Update MessengerSendFile function.
• Add MessengerReceiveFile function.

.gitlab-ci.yml

@@ -9,6 +9,7 @@ before_script:
   - mkdir -p ~/.ssh
   - chmod 700 ~/.ssh
   - ssh-keyscan -t rsa $GITLAB_SERVER > ~/.ssh/known_hosts
+  - ./xcode-remove-caches.sh
 
 stages:
   - test