Add persistent button to show/hide the sidebar

[yanlhomme]

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Is your feature request related to a problem? Please describe. Once the sidebar is shown and the user clicks on the arrow button it collapses and it isn't possible for the user to show it again. It would be nice to be able to show the sidebar again.

Describe the solution you'd like I suggest to keep the arrow button visible once the sidebar has been collapsed by the user such that he/she can display it again.

Describe alternatives you've considered

Additional context