inno: move inno installer files to contrib/packaging/inno
Let's isolate the inno installer files to their own directory
so the separation between things is clearer.
This required adjusting a few relative paths and references to
the old directory.
Differential Revision: https://phab.mercurial-scm.org/D6059
#require docutils gettext
$ $TESTDIR/check-gendoc pt_BR
checking for parse errors