Support providing a 'stack' configuration for 'as a library' usage

[manstis]

Description

Support providing the path to a llama-stack configuration file when using it "as a library".

Type of change

• Refactor
• New feature
• Bug fix
• CVE fix
• Optimization
• Documentation Update
• Configuration Update
• Bump-up dependent library
• Bump-up library or tool used for development (does not change the final image)
• CI configuration change
• Konflux configuration change

Related Tickets & Documents

• Related Issue #
• Closes #

Checklist before requesting a review

• I have performed a self-review of my code.
• PR has passed all pre-merge test jobs.
• If it is a core feature, I have added thorough tests.

Testing

• Please provide detailed steps to perform tests related to this code change.
• How were the fix/results from this change verified? Please provide relevant screenshots or results.

Try a configuration file:

name: foo bar baz
llama_stack:
  use_as_library_client: true
  library_client_config_path: /home/manstis/.llama/distributions/ollama/ollama-run.yaml
  url: http://localhost:8321
  api_key: xyzzy
  chat_completion_mode: true

[tisnik]

nice one, thank you!