Some further tidy-up in linear solver and complete second Frechet derivative implementation

Issue/feature addressed

• This MR complete the implementation of second-order Frechet derivate for the JFNK solver of the compressible flow solver
• Use (consistently) minimum tolerance of 1.0E-16 in linear solve.
• Use JacobiFreeEps = sqrt(NekConstants::kNekMachineEpsilon) for consistency with publication
• Rename blas.cpp as Blas.cpp
• Remove unused argument const NekDouble factor from NekSys.h class and subclasses
• Move member variables specific to GMRES from NekLinSysIter.h to NekLinSysIterGMRES.h and NekLinSysIterGMRESLoc.h
• Output both Res/Res0 and Res/DtRHS in Newton solver
• Use member variable m_converged in ConvergenceCheck

Proposed solution

Implementation

Tests

Suggested reviewers

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Notes

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Checklist

• Functions and classes, or changes to them, are documented.
• [ ] User guide/documentation is updated.
• Changelog is updated.
• Suitable tests added for new functionality.
• Contributed code is correctly formatted. (See the contributing guidelines).
• [ ] License added to any new files.
• No extraneous files have been added (e.g. compiler output or test data files).