feat: add OpenAI-compatible AI provider plugin with SSE streaming support

- Implemented the OpenAI-compatible AI provider plugin, including configuration, chat, and chat_stream functionalities.
- Added support for SSE streaming and tool calls.
- Integrated Boost.JSON for JSON handling.
- Created CMake configuration for the plugin.
- Added error handling and logging throughout the plugin.

plugins_middle/CMakeLists.txt

@@ -0,0 +1,7 @@
+# ============================================================
+# 依赖基础插件的插件 / Plugins depending on base plugins only
+# ============================================================
+
+add_subdirectory(network)      # 依赖 config / depends on config
+add_subdirectory(session)      # 依赖 file_io / depends on file_io
+add_subdirectory(tools)        # 依赖 file_io / depends on file_io