Add Process.Builder.output

[05nelsonm]

output should take in a Duration for timeout, and return stdout and stderr buffered output

[05nelsonm]

Adding the blocked label until #2 is completed

[05nelsonm]

Note that stdout and stderr must be Stdio.Pipe. This means the Stdio.Config.Builder should be a data class and it should be copied and updated before being passed as config to platform builder.

Either that, or it should throw an IOException

[05nelsonm]

Need to implement this for at least Jvm/Js in order to work out the APIs. Will help considerably when working on #2.

[05nelsonm]

With #31 , this is "completed" as the Jvm implementation is for nonJsMain, just need to link up nativeMain with the function once #2 is done for Native side of the house.