feat(runnable-rails): update RunnableRails with full LangChain Runnable protocol support

[Pouyanpi]

Description

• Complete rewrite of RunnableRails implementing full LangChain Runnable protocol
• Added comprehensive async/sync support for invoke, batch, and streaming operations
• Enhanced input/output handling for all LangChain message formats and chaining scenarios
• Extensive test suite with 14 test files covering batching, streaming, tool calling, and composition

requires #1364 and #1343 and #1289

[github-actions]

Documentation preview

https://nvidia.github.io/NeMo-Guardrails/review/pr-1366

[codecov-commenter]

Codecov Report

❌ Patch coverage is 77.25000% with 91 lines in your changes missing coverage. Please review.
✅ Project coverage is 71.65%. Comparing base (eb29437) to head (0c2a65e).

Files with missing lines	Patch %	Lines
...uardrails/integrations/langchain/runnable_rails.py	72.80%	90 Missing ⚠️
nemoguardrails/actions/llm/utils.py	98.18%	1 Missing ⚠️

Additional details and impacted files

@@             Coverage Diff             @@
##           develop    #1366      +/-   ##
===========================================
- Coverage    71.66%   71.65%   -0.01%     
===========================================
  Files          171      171              
  Lines        17015    17313     +298     
===========================================
+ Hits         12193    12406     +213     
- Misses        4822     4907      +85     

Flag	Coverage Δ
python	71.65% <77.25%> (-0.01%)	⬇️

Flags with carried forward coverage won't be shown. Click here to find out more.

Files with missing lines	Coverage Δ
nemoguardrails/context.py	100.00% <100.00%> (ø)
nemoguardrails/logging/verbose.py	90.90% <100.00%> (+0.39%)	⬆️
nemoguardrails/rails/llm/llmrails.py	90.52% <100.00%> (+0.06%)	⬆️
nemoguardrails/rails/llm/options.py	63.39% <100.00%> (+0.32%)	⬆️
nemoguardrails/actions/llm/utils.py	82.31% <98.18%> (+2.31%)	⬆️
...uardrails/integrations/langchain/runnable_rails.py	75.52% <72.80%> (-14.57%)	⬇️

... and 2 files with indirect coverage changes

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[Copilot]

Pull Request Overview

This PR completes a full rewrite of RunnableRails with comprehensive LangChain Runnable protocol support, providing async/sync operations, streaming capabilities, tool calling functionality, and enhanced input/output handling.

• Implemented complete LangChain Runnable protocol including invoke, batch, stream, and async variants
• Added tool calling support with proper context variable management across the pipeline
• Enhanced streaming functionality with proper chunk formatting and state management

Reviewed Changes

Copilot reviewed 26 out of 26 changed files in this pull request and generated 9 comments.

Show a summary per file

File	Description
tests/utils.py	Added streaming support to FakeLLM with _stream and _astream methods
tests/test_tool_calls_context.py	New test file for tool calls context variable functionality
tests/test_tool_calling_utils.py	New comprehensive tests for tool calling utility functions
tests/test_tool_calling_passthrough_integration.py	Integration tests for tool calling in passthrough mode
tests/runnable_rails/*.py	14 new test files covering streaming, batching, composition, and tool calling
nemoguardrails/rails/llm/options.py	Added tool_calls field to GenerationResponse model
nemoguardrails/rails/llm/llmrails.py	Enhanced to extract and include tool calls in responses
nemoguardrails/logging/verbose.py	Fixed potential AttributeError with missing record attributes
nemoguardrails/integrations/langchain/runnable_rails.py	Complete rewrite implementing full Runnable protocol
nemoguardrails/context.py	Added tool_calls_var context variable
nemoguardrails/actions/llm/utils.py	Refactored llm_call with tool calling support and improved message handling
examples/configs/nemoguards/*	New example configuration demonstrating NeMoGuard safety rails

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[tgasser-nv]

Looks good, just a few comments:

• ~4k LOC is too big for a single PR. Is there any way to stack multiple 100 - 400 line PRs or include something in the description link them?
• Can you run some tool calls locally to check all this works when calling production APIs?

[codecov-commenter]

Codecov Report

❌ Patch coverage is 72.80967% with 90 lines in your changes missing coverage. Please review.

Files with missing lines	Patch %	Lines
...uardrails/integrations/langchain/runnable_rails.py	72.80%	90 Missing ⚠️

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