feat: agent awareness of subagents conversation mode

[sovadim]

Applicable issues

• Make agent aware of subagents #88

Description of changes

Code changes:

• New field in deployment tool config - conversation_mode, enum, values: stateless (default), stateful;
• Deployment tool issues session_id, and injects into the tool schema;

Checklist

• Title of the pull request follows Conventional Commits specification
• Design documented is updated/created and approved by the team (if applicable)
• Documentation is updated/created (if applicable)
• Changes are tested on review environment
• App schema changes are backward compatible, or breaking changes are documented with a migration guide
• Integration tests pass

By submitting this pull request, I confirm that my contribution is made under the terms of the Apache 2.0 license.