(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