Add indicator_openai_api demo

[tonyleo723]

A new demo based on indicator_openai demo. Function change list below:

• Remove DALL-E function
• Added a command line that allows you to set the model provider url, model name and system prompt word by word, in addition to setting the api key
• Add a (half-finished) UI interface that can be used to set model call parameters
• Modify model call request logic and model response processing logic.

For more information, see the README.md file in the examples\indicator_openai_api directory.