RTF import: 3 drawing-object fixes:

This bring back the fdo#fdo42407 bugdoc to the state where it was around
4.0.

- fix dobxpage before dptxbx

The problem was that dobxpage arrived first, set HoriOrientRelation to
FRAME, then dptxbx tried to apply defaults, which overwrote the already
set HoriOrientRelation. Fix this by only applying properties which are
not set yet.

(cherry picked from commit 7c53577f325e5260c538f9ca42cda54ca1a24b7a)

- anchor drawing objects at-character by default

(cherry picked from commit d05b67a7b9448c67c3a923ecb33dac74b52dd192)

- fix ordering of old-style dhght in case of equal values

Commit 1eaab77c718ffa254068ae6032862dfb5a03db67 (fdo#60722 import
RTF_SHPZ, 2013-03-06) changed how we handle z-order, in case two shapes
have the same value. Turns out for drawing-objects the order is the
opposite in this situation.

So fix this by adding a new mode, that keeps the original testcase happy
without breaking older documents.

(cherry picked from commit e4fe3610eb17c441217c80536f0acf4123abd683)

Change-Id: Ib2d284cefc3c0dce40ac2e516ba260d6cd04ce43
Reviewed-on: https://gerrit.libreoffice.org/8621
Reviewed-by: Andras Timar <andras.timar@collabora.com>
Tested-by: Andras Timar <andras.timar@collabora.com>