cat-file: introduce batch_mode enum to replace print_contents
A future patch introduces a new --batch-command flag. Including --batch
and --batch-check, we will have a total of three batch modes. print_contents
is the only boolean on the batch_options sturct used to distinguish
between the different modes. This makes the code harder to read.
To reduce potential confusion, replace print_contents with an enum to
help readability and clarity.
Helped-by: Junio C Hamano <gitster@pobox.com>
Signed-off-by: John Cai <johncai86@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>