carousel: Support keynav

Fixes: GNOME/libhandy#146
11 jobs for carousel_keynav in 95 minutes and 22 seconds (queued for 2 seconds)
latest
Status Job ID Name Coverage
  Build
passed #744105
api-visibility

00:00:30

passed #744107
build-debian-clang

00:04:46

passed #744106
build-debian-gcc

00:50:40

passed #744108
build-fedora-gcc

00:08:54

passed #744109
flatpak
build-flatpak

00:01:27

passed #744110
flatpak
build-flatpak-glade

00:04:11

 
  Test+Docs
passed #744111
build-gtkdoc

00:35:45

passed #744112
unit-test

00:35:04

41.2%
 
  Package
passed #744113
package-debian-buster

00:03:47

 
  Test Package
passed #744114
autopkgtest-debian-buster-package

00:05:08

passed #744115
lintian-debian-buster-package

00:02:33