wrapper: Write stdout/stderr data to stream when received

[austinvalle]

Closes #395
Closes #405

This PR restores the equivalent of the wrapper's original behavior to immediately output to STDOUT and STDERR when data is received. I've attached a demo video of the new delayed test.

Context

Prior to #367, we relied on the @actions/exec package to immediately write to STDOUT and STDERR (which is the default behavior of silent: false), see the relevant underlying code.

Since we can't utilize the @actions/exec package's default behavior, due to the debug/command output being passed to the wrapper (actions/toolkit#649), we can just update our original listener to just write the data as it's being buffered. Shout out to @dannystaple for the original thought!

Demo

streaming-output.mov

[bflad]

Looks good to me (with my limited understanding of this part of NodeJS) 🚀

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