[kernel] Add test for `-commands-file`

.gitattributes

tests/misc/commands_file.t/comments_and_newlines.txt

tests/misc/commands_file.t/eva.txt

tests/misc/commands_file.t/full.txt

tests/misc/commands_file.t/kernel.txt

tests/misc/commands_file.t/ll_load.txt

tests/misc/commands_file.t/ll_save.txt

tests/misc/commands_file.t/prepro.txt

tests/misc/commands_file.t/print.txt

tests/misc/commands_file.t/run.t

tests/misc/commands_file.t/src.c

tests/misc/commands_file.t/src_empty.c

tests/misc/commands_file.t/with_error.txt