uno:InsertNarrowNobreakSpace/ FN_INSERT_NNBSP added and asigned to shift+alt+space

Change-Id: I20dd4159bc35ee378bee75af9734b1f25dfd8b1a
Reviewed-on: https://gerrit.libreoffice.org/66776
Tested-by: Jenkins
Reviewed-by: Heiko Tietze <tietze.heiko@gmail.com>