the reason is to make sure for blackoil cases, the same algorithm will
be used to invert the D matrix for the well model. As a result, it will
reduce the burden to test the PR.
Whether we will keep this algorithm for 4 X 4 matrix will be addressed
as a separate issue.
This replaces the makePreconditoner() function. The main advantage
is that it is extensible, making it easy to for example add new
preconditioners to the factory at runtime. It supports both parallel
and serial preconditioners.
Also use it in flow_blackoil_dunecpr.cpp. Adds new command-line parameter,
--linear-solver-configuration-json-file, to read linear solver config from
JSON-format file at runtime.
this is necessary because after OPM/ewoms#513, the
`SparseMatrixAdapter` property will be "owned" by the linear solver
and because ISTLSolverEbos does not build on top of
`Ewoms::ParallelBaseBackend`.
