Less prints to output

[amartyads]

currently every rank prints "Run CouetteScenario", "Finish CouetteScenario::initSolvers()" and "Finish CouetteScenario::shutdown() Shut down CouetteScenario" to the output. It floods output and makes manual scanning very cumbersome, and writes huge files with no actual data. We should remove these prints.

[rubenhorn]

In general there is a lot of std::cout << ... (1258 occurrences to be exact).
Perhaps we should (gradually) replace them with a logger that takes either verbosity level or tag as a parameter, a runtime parameter to filter before output and a default option in CMake.

[rubenhorn]

The logging function should also automatically include configurable additional information:

• The Unix timestamp of the output
• The MPI rank (How… call MPI_comm_rank every time? Seems excessive)
• The __FILE__ and __LINE__ of the log statement (Requires use of a macro, but I think it may be permissible if it is only used as a simple wrapper for the logging function)

[Thinkpiet]

@rubenhorn There is already a way to get the MPI rank anywhere, without passing it everywhere or calling MPI_comm_rank excessively: coupling::indexing::IndexingService<dim>::getInstance().getRank().

Note that it will always return the rank relative to the PinT domain (i.e. temporal subdomain if the simulation is time parallel), not the rank in MPI_COMM_WORLD, but I guess that is actually desired here. (For writing output to the logging system from time parallel simulations, the 'time local' rank AND the PinT domain number should be printed, not the global rank)