fall back to simple text output when stdout is not a tty

[knQzx]

summary

• detect when stdout is not a tty and fall back to simple line-by-line status output
• fixes silent commands when piping to a file

fixes #113

test plan

before (main):

$ container image pull ghcr.io/linuxcontainers/alpine:3.20 2>stderr.txt
$ cat stderr.txt
(empty - progress lost when stderr is not a tty)

after:

$ container image pull ghcr.io/linuxcontainers/alpine:3.20 2>stderr.txt
$ cat stderr.txt
[1/2] Fetching image [0s]
[1/2] Fetching image (7 of 15 blobs) [2s]
[1/2] Fetching image 42% (23 of 50 blobs, 10.0/23.7 MB, 6.9 MB/s) [5s]
[2/2] Unpacking image for platform linux/arm64 [11s]
...

also added TestCLIProgressAuto integration test covering auto/plain/none modes

[jglogan]

@knQzx Thank you for the PR! Could you please add the commands you tested with, and before/after output, to the PR description?

Would it be possible to add an integration test for this?

[knQzx]

added before/after output to the description and an integration test for this