mozc support in the default ISO

[Jeremy Bicha]

Qt4 was removed from the default Ubuntu 17.10 ISO this week as a
result of dropping fcitx support there. It looks like the only reason
Qt5 is still there is because ibus-mozc recommends mozc-utils-gui
which depends on Qt5. mozc is a Japanese input method but we do not
pre-install Japanese language packs in the live environment.

mozc was added to the live environment just before Ubuntu 15.10 was released:
https://bazaar.launchpad.net/~ubuntu-core-dev/ubuntu-seeds/ubuntu.artful/revision/2363

To use the mozc input method, I had to install ibus-mozc and then log
out of GNOME and log back in for it to show up in GNOME Settings >
Region & Language > Input Sources > + > … > Other > Japanese (Mozc) .
Since I have more than one input method/keyboard now, a language menu
shows up in the right side of the top bar. That menu allows switching
between 6 different mozc modes. gnome-control-center does not provide
any other mozc preferences.

mozc-utils-gui adds a "Mozc Setup" app. This app has a low-resolution
icon which doesn't look as good when people are browsing the list of
installed apps in the live environment. mozc-utils-gui allowing
customizing a lot of apparently useful mozc preferences.

Here are some follow-up questions:
1. Does it make sense to have ibus-mozc in the live environment but
without mozc-utils-gui?
2. It's hard for me to tell but mozc-utils-gui is possibly the only
thing keeping Qt in Ubuntu main. I guess we should consider whether
that app is important enough to stay in 'supported' if we do drop it
from 'live'.

Thanks,
Jeremy Bicha