Create an automated workflow to build official Docker images

[sabaimran]

• Add a dockerize workflow that allows us to pull from an official Cohere build. Would output to ghcr.io/cohere-ai/cohere-terrarium:latest.
• Support the workflow_dispatch command for manually triggering builds

Addresses #4

[arkadyark-cohere]

do we want to put this in the actions repo? https://github.com/cohere-ai/actions

[sabaimran]

@arkadyark-cohere I'll assume that question isn't meant for me, since I don't have access to that repo :). Happy to help if the action needs to be refit to work there.

[sabaimran]

Closing it out as it seems to not have gotten response. We'll maintain the image in our own fork for now.