[Feature]: Add tool hooks (tool_pre_invoke / tool_post_invoke) to plugin system #682
Description
Add tool hooks (tool_pre_invoke / tool_post_invoke) to plugin system.
Requirements
- Plugins with tool_pre_invoke hook should register to the pre-invocation hook of tool calls
- Plugins with tool_post_invoke hook should register to the post-invocation hook of tool calls
Implementation Notes
- Update PluginManager to implement lifecycle hooks and executors for tools
- Add/extend examples
- Add tests