leaflet: Rename allow-visible into navigatable

Fixes GNOME/libhandy#312
11 jobs for navigatable in 18 minutes and 35 seconds (queued for 1 second)
Status Name Job ID Coverage
  Build
passed api-visibility #828558

00:00:17

passed build-debian-clang #828560

00:03:47

passed build-debian-gcc #828559

00:02:02

passed build-fedora-gcc #828561

00:03:32

passed build-flatpak #828562
flatpak

00:01:15

passed build-flatpak-glade #828563
flatpak

00:03:13

 
  Test+Docs
passed build-gtkdoc #828564

00:03:43

passed unit-test #828565

00:02:25

44.2%
 
  Package
passed package-debian-buster #828566

00:06:16

 
  Test Package
passed autopkgtest-debian-buster-package #828567

00:04:46

passed lintian-debian-buster-package #828568

00:01:04