notification-content: Add close button on hover

This adds a close button when hovering with the mouse.  Modeled like
176354a2.

Signed-off-by: Guido Günther <guido.gunther@puri.sm>
18 jobs for hover-notify in 72 minutes and 51 seconds (queued for 3 seconds)
latest
Status Job ID Name Coverage
  Build
passed #311720
librem5
build:cross-debian-bullseye:i386

00:08:33

passed #311721
librem5
build:native-alpinelinux-edge

00:06:40

passed #311719
librem5
build:native-debian-bullseye

00:09:14

passed #311718
librem5
build:native-debian-buster

00:07:06

 
  Test+Docs
passed #311724
librem5
build-gtkdoc

00:04:13

passed #311726
librem5
check-license-headers

00:02:55

passed #311725
librem5
check-po

00:00:35

passed #311728
librem5
test:smoke:one-output

00:03:29

passed #311729
librem5
test:smoke:two-outputs

00:03:26

passed #311727
librem5
unit-test:native-alpinelinux-edge

00:00:39

passed #311723
librem5
unit-test:native-debian-bullseye

00:03:42

15.0%
passed #311722
librem5
unit-test:native-debian-buster

00:03:37

11.8%
 
  Package
passed #311731
librem5:arm64
package:deb-debian-bullseye:arm64

00:19:00

passed #311730
librem5
package:deb-debian-buster

00:10:06

passed #311732
librem5:arm64
package:deb-debian-buster:arm64

00:18:14

passed #311733
librem5
package:deb-pureos-amber

00:09:43

 
  Test Package
passed #311734
librem5
autopkgtest-debian-buster-package

00:01:05

passed #311735
librem5
lintian-debian-buster-package

00:00:32