give access to the extended help text for commands

(cherry picked from commit 3f483a92)

Conflicts:
	sfx2/inc/sfx2/sidebar/ControllerItem.hxx

Change-Id: I22668e6f9c1c7aed174a43d7d3e04829dc6733ae

Related: #i122433# fix build breaker

 invalid use of incomplete type 'struct Help'

(cherry picked from commit 797e3999)

Change-Id: Ifde6fede9b91eb828c665a5a720b93171108e17b