Assert a std::fs::read_to_string(path) value is less than another.
Pseudocode: std::fs::read_to_string(path1) < std::fs::read_to_string(path2)
let a ="alfa.txt"; let b ="bravo.txt"; assert_fs_read_to_string_lt!(&a, &b);
assert_fs_read_to_string_lt
assert_fs_read_to_string_lt_as_result
debug_assert_fs_read_to_string_lt