Unsaved item visibility/locked status in navigator can be overwritten when changing documents

To repro:

• Create a new project and add two rectangle items.
• Set one of them invisible (eyeball in navigator)
• Save document
• Toggle eyeball status of both rectangles, so that the other rectangle ends up invisible
• Without saving, exit designer mode and come back to it.

--> Both rectangles are invisible.

It seems that the auxiliary data is always read from the document on design mode open, and applied even if the document was already open and had unsaved auxiliary data.

Same thing happens with locked status.

This specific problem can be fixed by saving also "false" state into the auxiliary data instead of removing the data when locked/hidden state changes, but that will unnecessarily clutter the auxiliary data with false states, and doesn't address any other auxiliary data that might have the same issue. Unnecessary "false" hidden/locked values can also have some performance implications on the puppet side (though those could probably be worked around).