Add debug output option

[jmpolom]

When bootc shells out to external applications, such as during installation to sgdisk and systemd-cryptenroll, it should provide a way for the entire exact command to be logged or otherwise visible to the user for debugging purposes.

[jeckersb]

From:

bootc/lib/src/task.rs

Line 89 in 9a1e29c

tracing::debug!("exec: {cmd:?}");

Currently setting the environment RUST_LOG=debug should provide this with output like:

DEBUG exec: "ostree" "--repo=/ostree/repo" "rev-parse" "--single"

Is that sufficient? If so, at the very least it sounds like we could probably improve the docs to point this out.

[jmpolom]

I will try it and let you know what I find. It appears to do some kind of logging.

At a minimum a documentation improvement is needed to ensure that option is publicized, both on the website docs and in the help output from the (sub)command.

A flag would be far more user friendly than setting a random env var, particularly when dealing with the command running inside of a container. When running the command inside of the container you'd need to add an env var flag to the already very complex podman run invocation which will be tedious.

tldr; Adding a --verbose or --debug flag would be more user friendly/accessible than an env var.