Use Open AI Ada to convert input text to vector embeddings

[shivankacker]

Create a POST API endpoint called chat that accepts a text string, sends an API request to OpenAI Ada to convert into vector embeddings, and return the vector embeddings as a response (for now)

Take the OpenAi key from the environment with the name OPENAI_API_KEY. Edit core/settings/base.py to include the Environment variable. Default it to a blank string

For reference: https://platform.openai.com/docs/guides/embeddings/what-are-embeddings