Add dev container to open in GitHub Codespace

[blackgirlbytes]

I added a devcontainer to this repository along with instructions in the README for how a user can get started.

To test out this implementation, follow the steps for the README using either of the following:

1. GitHub Codespaces - VS Code Web Client
2. GitHub Codespaces - VS Code Desktop with GitHub Codespaces extension

It should work in the two indicated above.

What's happening in this PR?

• The devcontainer is handles opening up this environment, it runs the commands to install requirements and to run the main.py file.
• The devcontainer also indicates that the forwarded port should be on localhost:5003
• The devcontainer also automatically opens up two files for the developer's ease of use well-known/ai-plugin.json and openapi.yaml
• It also runs a bash script and enables permissions to run the bash script with chmod. This bash script automatically adds the Codespace forwarded port, so that developer's don't have to manual update those files to match the Codespace URL. I did this because your Codespace URL changes with each new Codespace and folks might forget to update it.
• I added instructions to the README.

Questions/Concerns

• The Codespace seemed to take a bit of a time to finish loading everything. Should I implement a pre-build?
• Are the instructions I added in the README too much? too little? too confusing?

Looking for review

I am looking for review from Logan and anyone on the Open AI team. I am also looking for review from anyone on the GitHub side, especially folks within the Codespaces team.

Thank you so much for this opportunity. It was fun!

cc: @logankilpatrick

[blackgirlbytes]

I wrote this DEV post to explain the changes that I made and help create awareness around Codespaces + ChatGPT plugins : https://dev.to/github/chatgpt-meets-github-codespaces-how-im-optimizing-chatgpt-quickstart-plugins-for-remote-development-5bc8

Hopefully this will be helpful for the OpenAI team and the Codespaces team.