pyuno: move "officehelper.py" from scripting to pyuno

... because at least in Fedora packages with system python it's a pain
to use officehelper.bootstrap() because unlike pyuno it is not installed
in the standard python directories but in libreoffice/program.

You might think that bootstrap() is not appropriate functionality for a
UNO langauge binding, but then why does ::cppu::bootstrap() exist?

Change-Id: I5fd4b344a811c087d32fb6304e55105ab3cb137e
Reviewed-on: https://gerrit.libreoffice.org/12968
Reviewed-by: Michael Stahl <mstahl@redhat.com>
Tested-by: Michael Stahl <mstahl@redhat.com>
(cherry picked from commit 8eb37e74fff1806608563ee49489b8a1f71fc6b0)