Handle xcresulttool stdout and stderr separately

[godrei]

Checklist

• I've read and followed the Contribution Guidelines
• step.yml and README.md is updated with the changes (if needed)

Version

Requires a PATCH version update

Context

iOS test result deployment can fail without a clear error messages about the problem, like:

Collecting test results...
Using new extraction method
Failed to parse extraction method: invalid character '+' looking for beginning of value
Falling back to legacy extraction method
Using legacy extraction method
Failed to parse test results: invalid character '+' looking for beginning of value

This PR improves on this issue, by handling xcresulttool stdout and stderr separately.

[tothszabi]

Can this be more like 10?

In the past we had such a thing where Xcode could not load some library because it was already loaded and the first two lines of the garbage output was the same thing. We might lose some interesting bit of info with only logging the first three lines.

[godrei]

Updated in: a3f3ecd