Add missing files to gallery bullets makefile

They are used in Bullets & Numbering dialog, and in
sidebar Bullets popup.

Change-Id: I543cad1108f8c45cc3dcc56a0c42fda2fbeb5467
Reviewed-on: https://gerrit.libreoffice.org/8125
Reviewed-by: Caolán McNamara <caolanm@redhat.com>
Tested-by: Caolán McNamara <caolanm@redhat.com>
(cherry picked from commit d8680de7012fb92a393066c957f82e1473b60575)
Reviewed-on: https://gerrit.libreoffice.org/8145
Reviewed-by: Kohei Yoshida <libreoffice@kohei.us>
Tested-by: Kohei Yoshida <libreoffice@kohei.us>