fdo#64047: n#863021: Add set-all language menu.

Problems:
* Doesn't reset the spell error markers
* Modifies only at object level
* Currently has only setting for 'all text'
* Maybe provide a current slide only option?

Change-Id: I4695423fed3ed9422185b23803eedd12ef434bea
(cherry picked from commit 0833f4046a1afa77aeed97a131c5325c44be1bb3)
Signed-off-by: Andras Timar <andras.timar@collabora.com>
Reviewed-on: https://gerrit.libreoffice.org/9314
Reviewed-by: Caolán McNamara <caolanm@redhat.com>
Tested-by: Caolán McNamara <caolanm@redhat.com>