Bug 14252: Move OPAC lang switcher to masthead navbar

Bug 14252: Move OPAC lang switcher to masthead navbar

The OPAC language switcher takes up a lot of space at the bottom of the
browser. It also has issues of being not always visible.
This patch adds the switcher to the masthead navbar and removes from the
opac-bottom.inc navbar.

Test plan
=========

1/ Apply patch
2/ Set opaclanguagesdisplay syspref to 'show'.
3/ Add a few languages i.e. es-ES, fr-FR and de-DE
     $ cd misc/translator
     $ perl translate <langcode>
4/ Enable installed languages for OPAC use by checking on 'opaclanguages'
   under I18N/L10N sysprefs
5/ Go to the OPAC, you should have a "Languages" dropdown on the masthead
   navbar, the opac-bottom.inc navbar should no longer be there.

Signed-off-by: Bernardo Gonzalez Kriegel <bgkriegel@gmail.com>
Works, no koha-qa errors.
Followup fix language chooser for sublanguages

Signed-off-by: Mark Tompsett <mtompset@hotmail.com>
Signed-off-by: Jonathan Druart <jonathan.druart@koha-community.org>
Signed-off-by: Tomas Cohen Arazi <tomascohen@theke.io>