Reduce build output until there is an error

[jxstxn1]

I think it would be nice to reduce the build output of this plugin as long as no error is occurring and instead print on which step the plugin is currently working

[passsy]

It just shows stdout/stderr of xcodebuild, nothing more. This is valuable for two reasons:

• in cases errors happen, the ouput contains relevant information what went wrong
• iOS build processes can take a long time. Like 20min, in some cases. In those cases you want to know if something is happening, or if xcodebuild is just hanging, waiting for the input in some UI.

But we could improve it. Like posting stdout/stderr only on error. Or show a loading indicator, some progress bar which could be possible.

We could even detect interactive shells (usually on your local machine) and then hide it, whereas it is automatically shown on CI systems.