The SfxStatBar_Impl struct only has a single StatusBarId
member. Use StatusBarId directly instead and drop the
struct.
Change-Id: Icc56290e3024baf83ae3e08da82749cec1b7b675
Reviewed-on: https://gerrit.libreoffice.org/c/core/+/208115
Tested-by: Jenkins
Reviewed-by: Michael Weghorn <m.weghorn@posteo.de>