Allow Ctrl+Tab and Ctrl+Shift+Tab in Shortcuts
Allow in GNOME Terminal Ctrl+Tab and Ctrl+Shift+Tab in Shortcuts, e.g. to use for Switch to Previous Tab and Switch to Next Tab.
At the moment, when one is trying to use them as a shortcut here, it is not possible and an error sound is heard.
When setting a shortcut in GNOME Terminal, a check can be done to test if Ctrl+Tab is not used in GNOME Shell Settings / Keyboard Shortcuts (gnome-control-center keyboard) and only then allow it for gnome-terminal. Idem for Ctrl+Shift+Tab.
If for one reason or the other, the user tries or manages to configure the same shortcut for both GNOME Terminal and GNOME Shell, it is handled just like any other shortcuts that is set in both places.
Implementing this gives the end user more freedom to set shortcuts when the specific shortcuts are not used elsewhere and otherwise remain unused.