New unittests to verify TileCache logic on the unit level.
Change-Id: Ia36181e850b349abb88ba5f04f1e5244771bacc6
Reviewed-on: https://gerrit.libreoffice.org/24574
Reviewed-by: Ashod Nakashian <ashnakash@gmail.com>
Tested-by: Ashod Nakashian <ashnakash@gmail.com>