JupyterLab keep restoring file modified outside of JupyterLab

[trungleduc]

In JupyterCAD and gluel-lab, we registered new document types with jupyter_ydoc to be able to modify them collaboratively.
If the document is opened in JupyterLab once, and then it is modified externally while JupyterLab is not running, the next time I open this document in Lab, the content is restored from the database. The only way to keep the new content is to remove the database in the current working directory.

From the server log, I believe this is the intention of jupyter_ydoc, but I feel like it creates a lot of confusion for a normal user. If there aren't technical constraints, I think we should allow users to disable this behavior or at least give them a warning before overwriting the file.

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