(cherry picked from commit a9f45f81)

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

Fixes #34

Fixes #32

It is already handled by the gtk subclass

(cherry picked from commit 7f96cdb7)

This reverts commit be014fca

See https://gitlab.gnome.org/GNOME/gnome-build-meta/-/merge_requests/1498#note_1367023

Cleanup in preparation of the next gtk-rs release

Closes #47, #46, #21, and #44

See merge request GNOME/gnome-tour!60

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

It is no longer used and if we ever re-add it, we can think of another way
to do that.

Fix last page button

See merge request GNOME/gnome-tour!62

(cherry picked from commit fc5a903f)

Fixes II

See merge request GNOME/gnome-tour!61

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

This would allow us to construct the pages on the ui files later