Fix: Sometimes not all tags are displayed

This fixes an issue where sometimes not all tags are displayed in the
sidebar. This is done by refreshing the tag list whenever the top level
item container's count changes (vs when an item is appended - this is
wrong, as the items are added in another thread).
17 jobs for 130-sometimes-not-all-tags-are-listed-in-the-sidebar in 8 minutes and 12 seconds (queued for 16 seconds)
Status Job ID Name Coverage
  Images
manual #41526623
allowed to fail manual
build_image_fedora
manual #41526624
allowed to fail manual
build_image_fedora_system
manual #41526625
allowed to fail manual
build_image_ubuntu
manual #41526626
allowed to fail manual
build_image_win32
manual #41526628
allowed to fail manual
build_image_win64
 
  Build
passed #41526629
linux_builtin

00:03:04

passed #41526631
linux_system

00:03:07

manual #41526640
macos allowed to fail manual
macos
passed #41526632
ubuntu_appimage

00:04:54

passed #41526634
win32_build

00:04:17

manual #41526637
windows allowed to fail manual
win32_vs_build
passed #41526636
win64_build

00:04:18

manual #41526639
windows allowed to fail manual
win64_vs_build
 
  Installer
passed #41526642
win32_installer

00:01:56

manual #41526645
allowed to fail manual
win32_vs_installer
passed #41526644
win64_installer

00:03:05

manual #41526646
allowed to fail manual
win64_vs_installer