Added functionality to add image to the text area. Currently working on being able to scale and move the image.

1. New file browser which browses server files.
2. FETCH feature implemented: users can fetch and get latest update from server. It will update related windows' content.
3. UPDATE feature implemeted: users can update thier work to the server.
4. FETCH feature is possible in file browser.
5. Delete in server side will not affect locally.
6. DELETE in local side will not affect server.

MULTI WINDOW Synching is now working: when there is changes in opened window after sync, it will update all windows' title and content

Synh DB logic not implemented yet.

1. when the file browser is opened elsewhere, the note cannot be deleted.
2. when we try to open the file which is already opened, opened file will gain focus.

JUNIT5 has been added in dependencies in all gradle files. Implemented two unit tests for file management. Fixed bug.