feat(iorails): Support non-streaming GenerationResponse

[tgasser-nv]

• Initial checkin of GenerationResponse code (non-streaming only, no token usage)
• Promote options to a named argument rather than smuggled in through kwargs

Description

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Checklist

• I've read the CONTRIBUTING guidelines.
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• My PR title follows the project commit convention.
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[codecov]

Codecov Report

❌ Patch coverage is 97.10145% with 6 lines in your changes missing coverage. Please review.

Files with missing lines	Patch %	Lines
nemoguardrails/guardrails/iorails.py	94.73%	6 Missing ⚠️

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