The kashida candidate position selection logic was copied-and-pasted from Writer into Edit Engine. This change consolidates the shared code into a library. This change also adds some minimal characteristic tests, which previously did not exist. Change-Id: I2bfbfa79858347803474b754566436f3e74d1a54 Reviewed-on: https://gerrit.libreoffice.org/c/core/+/173883 Reviewed-by: Jonathan Clark <jonathan@libreoffice.org> Tested-by: Jenkins