This only leaves us with only one translatable string defined on a rust file,
due to the low gettext/rust support...

It is nowadays similar to the ImagePageWidget, so let us just use that

Instead of doing multiple overlays, do a single overlay containing all
buttons as type=overlay children. This makes the carousel span the
window from start to end.

This allow us to simplify the changes on the UI part

it doesn't make much sense now, but it will do once we port the rest of widgets as well

makes iteration on the UI slower

* .page-body is indistinguishable from the default body style
* libadwaita uses .title-1, so .page-title can be swapped out
* .large-title was unused
* Other empty styles removed

The defaults work fine.

This commit upgrades our rust dependencies and ports
Tour to libadwaita+GTK4. As part of porting we now use
GtkPicture instead of GtkImage, and AdwClamps to hold pages
in place.

This port is part of https://gitlab.gnome.org/GNOME/Initiatives/-/issues/26 and handles https://gitlab.gnome.org/GNOME/Initiatives/-/issues/32

Fixes https://gitlab.gnome.org/GNOME/gnome-tour/-/issues/36

fixes https://gitlab.gnome.org/GNOME/gnome-tour/-/issues/45

- clean up unused pages
- add keyboard overview
- add search
- reword

Fixes https://gitlab.gnome.org/GNOME/gnome-tour/-/issues/41
Fixes https://gitlab.gnome.org/GNOME/gnome-tour/-/issues/42

tweak super key illustration

tweak super key illustration

- more of an adventure tour vibe

- avoid baloon duplicty

as the 'close' button is smaller, there's a weird
allocation thing when going from page 1 to page 2 for the first time

fixes #28

- make rocket more visible

- Fullcolor tour
- Basic CSS keyframe animations
- Use of default grey backgrounds due to headerbar

Fixes https://gitlab.gnome.org/GNOME/gnome-tour/-/issues/29

Tour is not an app because it has NoDisplay=true in its desktop file.
Therefore, it should not install appstream metainfo. This could be
brought back in the future if the desktop file is made visible.

See discussion in:

https://gitlab.gnome.org/GNOME/gnome-software/-/issues/445

https://gitlab.gnome.org/GNOME/gnome-software/-/issues/445