Remove not work provider

Update provider llama2

Add provider flowgpt

Change the installation method of xmake

Update ci to clang19

Remove freechatgpt,chatxyz,chatGptAi,chatGptDemo,gptGo,aiChatOnline,gpt6

Update llama2

Add provider FreechatGpt

Update xmake to 2.8.6

Add provider GeminiProChat

Fix header file path

Add provider chatxyz

Add provider gpt6

Auto load environment variables

Add provider aura