Add information linear and non-linear solver outputs

[hepap]

Description of the problem

• The console output of the non-linear solver in the NS solver was showing the the norms of the newton update without distinction between the velocity and pressure contributions.
• The final residual norm of the linear solver was not outputted, only the tolerance.

Description of the solution

• Add the distinction between the velocity and pressure contributions in the non-linear solver output.
• Add the final value of the linear residual when verbosity is at verbose. If it is at extra verbose, the solver output the residual for each iteration (already implemented but not documented).

How Has This Been Tested?

A unit test was added.

• [x] vector_problem.cc

Documentation

Add a comment for the extra verbose verbosity of the linear solver.

• [x] linear_solver_control.rst

[hepap]

I think it is ready to merge if the tests pass! The output was added for CH as well :)

[blaisb]

@hepap some tests are breaking, can you double check them?

[hepap]

Should be alright now!