fdo#74573: Delete ranges that are non-empty before pasting from clipboard.

The conditional formatting part is still not working. But other bits
appear to be working now.

Also, adjust handling of mix document aka paste functions with this
change.  When using paste function (add, subtract, etc), the behavior
between the 'skip empty' flag on and off makes no difference.  Let's
set the flag to off when paste function is used.

(cherry picked from commit 0c12aa670b83b76241077dfb8bc21f40a55b1667)
(cherry picked from commit 2f55cee39379a76920f3a4fb14e6c2774093bfcd)
(cherry picked from commit cdc8ebf9646e773351c91039a62f2414c7b02105)

Conflicts:
	sc/inc/clipcontext.hxx
	sc/inc/column.hxx
	sc/inc/document.hxx
	sc/inc/table.hxx
	sc/source/core/data/clipcontext.cxx
	sc/source/core/data/column4.cxx
	sc/source/core/data/document10.cxx
	sc/source/core/data/table7.cxx

Change-Id: I67724ba923c9260b2c14464e4123b8445712dbaf
Reviewed-on: https://gerrit.libreoffice.org/7906
Reviewed-by: Markus Mohrhard <markus.mohrhard@googlemail.com>
Tested-by: Markus Mohrhard <markus.mohrhard@googlemail.com>