More configuration for `Process` stdin/stdout/stderr streams

[armanbilge]

Follow up to:

• Introduce Process API #3149 (comment)

The idea is to support various sinks/sources for streams related to a Process. For example, merging stderr into stdout, or reading/writing to a file.

[Dralt03]

Hey I would like to work on this issue. Can you give a little more background on the problem
From what I understand we have to use the redirectErrorStream funtion to io/jvm-native/src/main/scala/fs2/io/process/ProcessesPlatform.scala for merging the stderr and stdout