feat: add command output/error option

[schomatis]

Add an option to save command output to a file instead of the stdout argument (which was always set to stdout by go-ipfs consumer). We have removed the option and assumed stdout except the option is set (this was intended to loudly flag the output is being set by an option since the argument could be misleadingly overridden, but we can restore the argument and have the two coexist).

Used in ipfs/kubo#8683.

Related to ipfs/kubo#8335.

[lidel]

I suspect stdout is not enough. My concern is that stderr would not end up in the (empty) file, but would go to terminal:

$ ipfs id --command-output=stdout.txt
Error: no IPFS repo found in /home/lidel/tmp/go-ipfs-out.
please run: 'ipfs init'

$ ipfs get invalidcid --command-output=stdout.txt
Error: invalid path "invalidcid": selected encoding not supported

If someone runs a command in bash script, they may not monitor stderr and the message may be lost.

Perhaps an elegant way of handling this is to have explicit --stdout (or --output) and --stderr (or --errors) ?

$ ipfs get invalidcid --stdout=stdout.txt --stderr=stderr.txt
$ cat stdout.txt 
$ cat stderr.txt
Error: invalid path "invalidcid": selected encoding not supported

cc @aschmahmann you may have better intuition about what would be the most useful on windows

[schomatis]

@lidel Added error output option (we can review the option names at the end; I'm leaving for now the conspicuous --command-output/error for visibility).