Add settings page for Panels

Add settings page for Panels

For now this just includes the settings for the information panel.

Prior to this commit the options for configuring the information panel
were only exposed via right clicking the information panel. This was
not discoverable enough. Our guidelines also state that much. See:
https://community.kde.org/Get_Involved/Design/Frequently_Discussed_Topics#Context_menus_are_not_enough

The settings page is missing the "Configure" button for the entries in
the information panel, which can only be found in the context menu.
This is because I thought it would be weird to move it to the settings
page. (The "configure" button is used to select the entries for the
information panel)

BUG: 480243
FIXED-IN: 24.05