GMRES sets success flag to true if the initial guess is already converged

[michelebucelli]

Fixes #573:

1. the success flag is now set to true in GMRES if the initial guess is already good enough, so that no "solution has not converged" warnings are raised;
2. the success flag itself is renamed from suc to success for improved readability.

Code of Conduct & Contributing Guidelines

• I agree to follow the Code of Conduct and Contributing Guidelines.

[claude]

Claude Code Review

This pull request is from a fork — automated review is disabled. A repository maintainer can comment @claude review to run a one-time review.

[michelebucelli]

Partially related to this: I asked AI to double-check that I'd caught all instances of suc to be renamed to success (I don't have PETSc on my local build so I might have missed some), and it observed that there's a solver/gmres.cpp file that is nearly identical to linear_solver/gmres.cpp, but is never compiled (it's not listed in solver/CMakeLists.txt).

Perhaps it is a leftover from an older organization of the code? In which case, it might be worth removing it to clean it up, as part of this PR.

It also flagged a number of similarly dead code in the class lsType from ComMod.h.

[codecov]

Codecov Report

❌ Patch coverage is 97.72727% with 1 line in your changes missing coverage. Please review.
✅ Project coverage is 69.45%. Comparing base (9632608) to head (7ee150a).

Files with missing lines	Patch %	Lines
Code/Source/solver/output.cpp	85.71%	1 Missing ⚠️

Additional details and impacted files

@@           Coverage Diff           @@
##             main     #574   +/-   ##
=======================================
  Coverage   69.44%   69.45%           
=======================================
  Files         181      181           
  Lines       34072    34077    +5     
  Branches     5930     5930           
=======================================
+ Hits        23662    23667    +5     
  Misses      10273    10273           
  Partials      137      137           

☔ View full report in Codecov by Harness.
📢 Have feedback on the report? Share it here.

🚀 New features to boost your workflow:

• ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.