Remove the Karniadakis time solver

CHANGELOG.md

CMakeLists.txt

examples/IMEX/advection-reaction/data/BOUT.inp

examples/constraints/laplace-dae/data/BOUT.inp

examples/eigen-box/data/BOUT.inp

examples/elm-pb/eigen/BOUT.inp

examples/gravity_reduced/data/BOUT.inp

examples/gyro-gem/data/BOUT.inp

examples/hasegawa-wakatani/data/BOUT.inp

examples/jorek-compare/data/BOUT.inp

include/bout/solver.hxx

manual/sphinx/user_docs/time_integration.rst

src/solver/impls/karniadakis/karniadakis.cxx

src/solver/impls/karniadakis/karniadakis.hxx

src/solver/impls/karniadakis/makefile

src/solver/impls/makefile

src/solver/solver.cxx

tests/integrated/test-delp2/data/BOUT.inp

tests/integrated/test-solver/test_solver.cxx