patch 9.0.1749: Text property highlight doesn't override a sign highlight on TAB

patch 9.0.1749: Text property highlight doesn't override a sign highlight on TAB

Problem: Text property highlight doesn't override a sign highlight over
         a tab character
Solution: Let text_property override tab highlighting

This fixes a few problems of text properties:

-  text property highlighting when override=true does not overwrite TAB
   highlighting
-  text property highlighting when override=true does not overwrite TAB
   highlighting with :set list
-  text property highlighting is used instead of sign highlight after
   the actual text ends when signs are present with linehl is set

closes: #21584
closes: #21592

Signed-off-by: Christian Brabandt <cb@256bit.org>