Read_RTLJustify knows that it needs to swap in BiDi situations,
but sometimes it is read before BiDi status is known.
So Read_ParaBiDi needs to watch for this and do the swap afterwards.

Three situations to handle:
1.) bidi same as previous setting: no adjust change
2.) no previous adjust: set appropriate default for this bidi
3.) previous adjust and bidi different from previous: swap adjusts
(4. Unknown bidi treated like prev=LTR - one difference from DOCX)

Unit tests cover both situations - where BiDi is already known,
and where it is unknown.

Change-Id: I0b4e2383a4909fe79317dd9772d0be63f749da68
Reviewed-on: https://gerrit.libreoffice.org/57294
Tested-by: Jenkins
Reviewed-by: Justin Luth <justin_luth@sil.org>