Feature: Improve local development setup

[jmnmv12]

Changelog

This PR introduces a couple of changes to improve the local development setup:

• Add a new optional config S3_endpoint_url that allows the user to specify a different S3 URL from the standard AWS one. This is especially useful when using S3 mocks locally
• Small refactor on the utils/s3.py logic to aggregate the s3 client initialization logic into a single method
• Add a docker-compose.yaml file that allows the developer to run the Postgres DB, Adobe S3 mock and the api service with a single command. This should only be used for development purposes
• Improve root project documentation on how to run the services locally

[clementblaise]

In my branch for openrouter I had made the changes for S3 endpoint, should I removed them or cherry picking here makes more sense?

[jmnmv12]

In my branch for openrouter I had made the changes for S3 endpoint, should I removed them or cherry picking here makes more sense?

Me and @clementblaise synced and since this PR is smaller and will probably be merged first we think it's best to keep the S3 changes here and then Clement can merge these changes into his branch 👌