Clean-up edition-related things

See merge request GNOME/gnome-tour!18

assets: lower contrast on Fragments icon

See merge request GNOME/gnome-tour!17

- get rid of the purple. The joys of a colorblind designer

addresses concern https://gitlab.gnome.org/GNOME/gnome-tour/-/issues/17#note_886067

assets: Software grid alignment

See merge request GNOME/gnome-tour!15

- align Software icon
- adjust grid position and alignment
- replace some app icons

See https://gitlab.gnome.org/GNOME/gnome-tour/-/issues/17

We no longer need to manually keep it in sync with the ci.

Fix minor typo: tying -> typing

See merge request GNOME/gnome-tour!14

Update labels

Closes #18

See merge request GNOME/gnome-tour!12

assets: tweak page #6

See merge request GNOME/gnome-tour!13

- Add dropshadow for the Software icon, replace Banner viewer with
  Foliate

Based on design review https://gitlab.gnome.org/GNOME/gnome-tour/-/issues/17

General polish for the page text.

Fixes #18.

paginator: Update position after adding pages

See merge request GNOME/gnome-tour!10

Otherwise it's mixed state until we swipe carousel the first time or
press Next.

Some UI cleanups

See merge request GNOME/gnome-tour!9

Use with_label() instead of a manually created label, make the headerbar
ones translatable, add mnenonics everywhere.

Take the position and round it, make the transition a bit more responsive.

Remove redundant properties, stop setting width request. Add a size group
and put both buttons into it so that they always have the same width.

Separate next and close buttons, do a stick-to-finger crossfade on last
page.

This is necessary to load the styles, needed for HdyWindowHandle to be
draggable (yay style properties) and for HdyWindow to have proper corners.