feature: support tool-calling messages in check_async()

[m-misiura]

Did you check the docs?

• I have read all the NeMo-Guardrails docs

Is your feature request related to a problem? Please describe.

check_async() does not handle tool-calling conversation patterns

Describe the solution you'd like

• Accept tool_calls fields on assistant messages and role: tool messages in the check_async() input
• Route tool-related content through the appropriate tool_input / tool_output rails
• Return check results that reflect whether tool interactions passed or were blocked/modified

Describe alternatives you've considered

n / a

Additional context

No response

[m-misiura]

cc @Pouyanpi @tgasser-nv; if you think this is a good proposal, please assign me to it :)