#2183 switch to using the cell population writer hierarchy in cell populations.

git-svn-id: https://chaste.cs.ox.ac.uk/svn/chaste/trunk@18578 b5f69653-2bf5-0310-8201-b0dafb8e1405
#2183 fix build. Problem caused by `MeshBasedCellPopulationWithGhostNodes` previously writing cell type data for ghost nodes that have no cell attached

git-svn-id: https://chaste.cs.ox.ac.uk/svn/chaste/trunk@18580 b5f69653-2bf5-0310-8201-b0dafb8e1405
#2183 Fix nightly simulation. Fix coverage and add a layer of abstraction to the writer hierarchy.

git-svn-id: https://chaste.cs.ox.ac.uk/svn/chaste/trunk@18581 b5f69653-2bf5-0310-8201-b0dafb8e1405
#2183 missed a file.

git-svn-id: https://chaste.cs.ox.ac.uk/svn/chaste/trunk@18582 b5f69653-2bf5-0310-8201-b0dafb8e1405