* Split `CERES_NO_METIS` into two defines: `CERES_NO_PARTITION` and
`CERES_NO_METIS`. The former refers to METIS support in SuiteSparse,
the latter to the Eigen's MetisSupport module. This enables the use of
sparse matrix reordering independent from SuiteSparse.
* Run Linux, macOS, and macOS Github workflows with METIS enabled
SuiteSparse.
Fixes#808
Change-Id: I5076b7e1268d32cc3e7e56650edcbaf7fb3b59ce