Check coord_sys of SpatialVariable

[rtimms]

When creating a SpatialVariable check the coordinate system against KNOWN_COORD_SYS defined here.

[brosaplanella]

You beat me hahaha. The docstring also needs fixing.

[rtimms]

Also, add a setter for coord_sys is SubMesh to perform this check for the meshes too.

[kratman]

Is this solved by #3394 and #3114? This seems like a duplicate

[agriyakhetarpal]

Yes, Ferran mentioned in https://github.com/pybamm-team/PyBaMM/issues/3114#issuecomment-1648160595 that #3394 should close both issues. We should probably close this one and keep the newer one open.