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.

tests/openai_plugin_test.cpp

@@ -9,7 +9,7 @@
  */
 #define BOOST_JSON_HEADER_ONLY
 #define BOOST_ALL_NO_LIB
-#include "../plugins/openai/src/openai_plugin.cpp"
+#include "../plugins_upper/openai/src/openai_plugin.cpp"
 
 #include <cstring>
 #include <iostream>