generate_packets.py: make files_equal() compare contents line by line
Part of #43927. Related to #45186. The files_equal() helper function (which is used by lazy-overwrite) currently loads both input files completely ~> make it use the fact that TextIO objects are iterable to compare them line by line
Depends on #45186 (or rather, its parts):
Part of #43927. Related to #45186. The files_equal() helper function (which is used by lazy-overwrite) currently loads both input files completely ~> make it use the fact that TextIO objects are iterable to compare them line by line