Check that we never panic in the test framework

[bjorn3]

Basically when creating an Output value already check that stderr doesn't contain the word panic and that the exit code is not 101.

sudo-rs/test-framework/sudo-test/src/docker/command.rs

Lines 213 to 235 in 71a2eb7

	impl TryFrom<process::Output> for Output {
	type Error = Error;
	fn try_from(output: process::Output) -> std::result::Result<Self, Self::Error> {
	let mut stderr = String::from_utf8(output.stderr)?;
	let mut stdout = String::from_utf8(output.stdout)?;
	// it's a common pitfall to forget to remove the trailing '\n' so remove it here
	if stderr.ends_with('\n') {
	stderr.pop();
	}
	if stdout.ends_with('\n') {
	stdout.pop();
	}
	Ok(Output {
	status: output.status,
	stderr,
	stdout,
	})
	}
	}