Bug 19570: Add autocomplete to opac-main as well

Bug 19570: Add autocomplete to opac-main as well

To confirm all the files were modified for opac, typed
this:
$ git grep -i password | grep opac | grep -v "[.]po:" | grep
"opac[^/]*[.]tt:" | cut -f1 -d: | sort -u

The follow output was handled as follows:
    koha-tmpl/opac-tmpl/bootstrap/en/modules/opac-auth.tt
    koha-tmpl/opac-tmpl/bootstrap/en/modules/opac-memberentry.tt
    koha-tmpl/opac-tmpl/bootstrap/en/modules/opac-passwd.tt
    koha-tmpl/opac-tmpl/bootstrap/en/modules/opac-registration-confirmation.tt
These were already done in the first patch.

    koha-tmpl/opac-tmpl/bootstrap/en/modules/opac-password-recovery.tt
This already had the autocomplete modification.

    koha-tmpl/opac-tmpl/bootstrap/en/modules/opac-detail.tt
This was a false-find. There was no modification necessary.

    koha-tmpl/opac-tmpl/bootstrap/en/modules/opac-main.tt
This is the modal login in. This patch amends it.

Signed-off-by: Katrin Fischer <katrin.fischer.83@web.de>
Signed-off-by: Marcel de Rooy <m.de.rooy@rijksmuseum.nl>
Signed-off-by: Jonathan Druart <jonathan.druart@bugs.koha-community.org>