Add `chat-ui` and `chat-ui-db` docker images (#613)
* Add a `Dockerfile.local` image to build
* Add a build & publish workflow
* fix workflow
* Add support for local mongoDB
* Fix problem with POST requests
* use slim image
* Set mistral to be the default model in .env
* Fix entrypoint
* Revert change regarding config folder
* replace env variable by build arg for DB and update work
* old mention of `conf` folder in readme
* env to .env
* Revert readme changes
* lint
