[Ecosystem] Add libraries to send outputs and metrics from R, Node.js and Powershell script tasks

Currently, you can send outputs and metrics in Python and Shell scripts e.g. `Kestra.outputs({'status': response.status_code, 'text': response.text})`. It's worth adding equivalent libraries for other script plugins, too.

Additionally, for each language we'll need to guarantee that all logs emitted by that task are captured with the same log level in kestra — this may require similar work to https://github.com/kestra-io/libs/pull/6

Start by reviewing how Python and Shell script tasks currently send outputs and metrics, then compare the linked libs pull request for log capture patterns. Define equivalent behavior for R, Node.js, and PowerShell, including preserving task log levels. Done means each language can send outputs and metrics and captures its task logs consistently.

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