Upgrade `sfg.method` sequencer.

src/pystencilssfg/composer/basic_composer.py

src/pystencilssfg/composer/class_composer.py

src/pystencilssfg/emission/file_printer.py

src/pystencilssfg/ir/entities.py

tests/generator_scripts/index.yaml

tests/generator_scripts/source/ComposerFeatures.harness.cpp

tests/generator_scripts/source/ComposerFeatures.py

tests/generator_scripts/source/SimpleClasses.py