Since commit ae0e830f, mirroring
is handled correctly in LO, so no need to handle it specially in
PDF import code. Commit 11c86503
fixed import to Draw, this one fixes import to Writer.
Also, unit tests for both cases are provided.

Change-Id: I9ef9753a364af34f9e158052855c5dba1300c934
Reviewed-on: https://gerrit.libreoffice.org/23028Tested-by: Jenkins <ci@libreoffice.org>
Reviewed-by: Caolán McNamara <caolanm@redhat.com>
Tested-by: Caolán McNamara <caolanm@redhat.com>