Add macro OOO_DLLPUBLIC_TEST to class XIndexAccess (needed to use the
test cases), refactor ctor, and add missing header files.

Change-Id: Id8b27c8c3a3d7fc5c64fafd25b0d9b4b511c281f
Reviewed-on: https://gerrit.libreoffice.org/64375
Tested-by: Jenkins
Reviewed-by: Jens Carl <j.carl43@gmx.de>