Animate the Sidebar Objects Tree view opening/closing

# Current Behavior

The tree view opens without animation, confusing. (There is a sudden change of states that is hard to grasp.)

# Desired Behavior

We want to introduce an animation when opening the menu so the user doesn't feel lost.

The animation should be 300ms and look like this:

https://github.com/user-attachments/assets/a16fae23-4cb5-47c7-80fa-ed9edf3118a2