Static panel

If the panel is only shown in the overview, it currently slides in from the top. Especially with touch gestures, this feels a bit off, as the panel movement is not in sync with the workspace movement. This MR re-attaches the panel to the overviewGroup if hidden and removes all easing. Hence, the panel is rendered behind the workspaces like the Dash, the Workspace Overview and the Search Bar.

Some notes:

• I have only tested this on GNOME 43.
• I am not sure if the

  // hide and show can fix windows going under panel
  panelBox.hide();
  panelBox.show();

  is still required. For me, it also works without this.
• While testing, I noticed that there is too much padding at the top of the overview if the panel is shown at the bottom. Is this a known issue?

Before:

Screencast_from_2023-03-05_13-42-12

After:

Screencast_from_2023-03-05_13-40-32