feat: support response streaming on node env

[AlexCaston]

With this PR the node environment now supports response streaming by returning a Readable as the body from the fission function.

This environment can be tried with:

fission environment create --name nodejs-streaming --image ghcr.io/a-safe-digital/node-streaming-env:0.1.3

[Copilot]

Pull Request Overview

This PR adds response streaming support to the Node.js environment by allowing fission functions to return a Readable stream as the response body, which is then piped directly to the HTTP response.

• Imports the Readable class from node:stream module
• Adds conditional logic to handle Readable streams by piping them to the response instead of sending them directly

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[AlexCaston]

Hi @sanketsudake,

I just fixed the style issues mentioned by copilot.